MFC: r292180 (partial), r297127 (partial), r311911, r311923, r312939,
r313250, r313712, r314811 (partial), r314887 (partial), r315430,
r317981, r315466

o Move the DRIVER_MODULE() statements that declare mmc(4) to be a child
of the various bridge drivers out of dev/mmc.c and into the bridge
drivers.

o Add ACPI platform support for SDHCI driver.

o Fix some overly long lines, whitespace and other bugs according to
style(9) as well as spelling etc. in mmc(4), mmcsd(4) and sdhci(4).

o In the mmc(4) bridges and sdhci(4) (bus) front-ends:
- Remove redundant assignments of the default bus_generic_print_child
device method,
- use DEVMETHOD_END,
- use NULL instead of 0 for pointers.

o Trim/adjust includes.

o Add and use a MMC_DECLARE_BRIDGE macro for declaring mmc(4) bridges
as kernel drivers and their dependency onto mmc(4).

o Add support for eMMC "partitions". Besides the user data area, i. e.
the default partition, eMMC v4.41 and later devices can additionally
provide up to:
1 enhanced user data area partition
2 boot partitions
1 RPMB (Replay Protected Memory Block) partition
4 general purpose partitions (optionally with a enhanced or extended
attribute)

Besides simply subdividing eMMC devices, some Intel NUCs having UEFI
code in the boot partitions etc., another use case for the partition
support is the activation of pseudo-SLC mode, which manufacturers of
eMMC chips typically associate with the enhanced user data area and/
or the enhanced attribute of general purpose partitions.

CAVEAT EMPTOR: Partitioning eMMC devices is a one-time operation.

o Now that properly issuing CMD6 is crucial (so data isn't written to
the wrong partition for example), make a step into the direction of
correctly handling the timeout for these commands in the MMC layer.
Also, do a SEND_STATUS when CMD6 is invoked with an R1B response as
recommended by relevant specifications.

o Add an IOCTL interface to mmcsd(4); this is sufficiently compatible
with Linux so that the GNU mmc-utils can be ported to and used with
FreeBSD (note that due to the remaining deficiencies outlined above
SANITIZE operations issued by/with `mmc` currently most likely will
fail). These latter have been added to ports as sysutils/mmc-utils.
Among others, the `mmc` tool of mmc-utils allows for partitioning
eMMC devices (tested working).

o For devices following the eMMC specification v4.41 or later, year 0
is 2013 rather than 1997; so correct this for assembling the device
ID string properly.

o Let mmcsd.ko depend on mmc.ko. Additionally, bump MMC_VERSION as at
least for some of the above a matching pair is required.

MFC r294032:

Fix the handling of the "PDC write transfer length" erratum for at91. The
problem affects revision 1xx hardware as well as later versions. Also, the
recommended workaround is to set the PDC count register for a 12-byte
transfer when the actual size is less than that, but there is no need to
extend or zero-out the data buffer, because the blklen register contains
the real transfer size and only that many bytes will be transferred.

Also add a sysctl to turn debugging printfs on or off on the fly.

MFC r261681, r261682, r261683, r261684, r261685, r261686, r261687, r261688,
r261689, r261690, r261783, r261791, r261836, r261837, r261841,

Add FDT matching code to AT91 device drivers.

Better nomatch messages: include compat string. Also, flag devices as
disabled in the successful probe message, but leave what that means to
the actual driver (no semantic changes).

Fix Embest board name and id.

Honor the disabled status by only grabbing resources and returning
when running under FDT in the AT91 SPI driver.

MFC r257199, r257200, r257217:

Remove all #include <machine/pmap.h> from arm code. It's already
included by vm/pmap.h, which is a prerequisite for arm/machine/pmap.h
so there's no reason to ever include it directly.

Remove #include <machine/frame.h> from all the arm code that doesn't
really need it. That would be almost everywhere it was included. Add
it in a couple files that really do need it and were previously getting
it by accident via another header.

Remove the last dregs of trapframe_t. It turns out only arm was using
this type, so remove it to make arm code more consistant with other
platforms.

MFC r261681, r261682, r261683, r261684, r261685, r261686, r261687, r261688,
r261689, r261690, r261783, r261791, r261836, r261837, r261841,

Add FDT matching code to AT91 device drivers.

Better nomatch messages: include compat string. Also, flag devices as
disabled in the successful probe message, but leave what that means to
the actual driver (no semantic changes).

Fix Embest board name and id.

Honor the disabled status by only grabbing resources and returning
when running under FDT in the AT91 SPI driver.

MFC r257199, r257200, r257217:

Remove all #include <machine/pmap.h> from arm code. It's already
included by vm/pmap.h, which is a prerequisite for arm/machine/pmap.h
so there's no reason to ever include it directly.

Remove #include <machine/frame.h> from all the arm code that doesn't
really need it. That would be almost everywhere it was included. Add
it in a couple files that really do need it and were previously getting
it by accident via another header.

Remove the last dregs of trapframe_t. It turns out only arm was using
this type, so remove it to make arm code more consistant with other
platforms.