Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Mechanically substitute flags from historic mbuf allocator with
malloc(9) flags in sys/dev.

Remove duplicate const specifiers in many drivers (I hope I got all of
them, please let me know if not). Most of these are of the form:

static const struct bzzt_type {
[...list of members...]
} const bzzt_devs[] = {
[...list of initializers...]
};

The second const is unnecessary, as arrays cannot be modified anyway,
and if the elements are const, the whole thing is const automatically
(e.g. it is placed in .rodata).

I have verified this does not change the binary output of a full kernel
build (except for build timestamps embedded in the object files).

Reviewed by: yongari, marius
MFC after: 1 week

ether_ifattach() sets if_mtu to ETHERMTU, don't bother set it again

Reviewed by: yongari

- There's no need to overwrite the default device method with the default
one. Interestingly, these are actually the default for quite some time
(bus_generic_driver_added(9) since r52045 and bus_generic_print_child(9)
since r52045) but even recently added device drivers do this unnecessarily.
Discussed with: jhb, marcel
- While at it, use DEVMETHOD_END.
Discussed with: jhb
- Also while at it, use __FBSDID.

Remove variable initialized but no longer actually used since r226995.

Found with: Coverity Prevent(tm)
CID: 10044

- Import the common MII bitbang'ing code from NetBSD and convert drivers to
take advantage of it instead of duplicating it. This reduces the size of
the i386 GENERIC kernel by about 4k. The only potential in-tree user left
unconverted is xe(4), which generally should be changed to use miibus(4)
instead of implementing PHY handling on its own, as otherwise it makes not
much sense to add a dependency on miibus(4)/mii_bitbang(4) to xe(4) just
for the MII bitbang'ing code. The common MII bitbang'ing code also is
useful in the embedded space for using GPIO pins to implement MII access.
- Based on lessons learnt with dc(4) (see r185750), add bus barriers to the
MII bitbang read and write functions of the other drivers converted in
order to ensure the intended ordering. Given that register access via an
index register as well as register bank/window switching is subject to the
same problem, also add bus barriers to the respective functions of smc(4),
tl(4) and xl(4).
- Sprinkle some const.

Thanks to the following testers:
Andrew Bliznak (nge(4)), nwhitehorn@ (bm(4)), yongari@ (sis(4) and ste(4))
Thanks to Hans-Joerg Sirtl for supplying hardware to test stge(4).

Reviewed by: yongari (subset of drivers)
Obtained from: NetBSD (partially)

- Add IFM_10_2 and IFM_10_5 media via tlphy(4) only in case the respective
interface also has such connectors.
- In tl_attach() unify three different ways of obtaining the device and
vendor IDs and remove the now obsolete tl_dinfo from tl_softc.
- Given that tlphy(4) only handles the integrated PHYs of NICs driven by
tl(4) make it only probe on the latter.
- Switch mlphy(4) and tlphy(4) to use mii_phy_add_media()/mii_phy_setmedia().
- Simplify looking for the respective companion PHY in mlphy(4) and tlphy(4)
by ignoring the native one by just comparing the device_t's directly rather
than the device name.

Converted the remainder of the NIC drivers to use the mii_attach()
introduced in r213878 instead of mii_phy_probe(). Unlike r213893 these
are only straight forward conversions though.

Reviewed by: yongari

- Hook into the existing stat timer to drive the transmit watchdog instead
of using if_watchdog and if_timer.
- Reorder detach to call ether_ifdetach() before anything else in tl(4)
and wb(4).

Use the bus_*() routines rather than bus_space_*() for register operations.

Use if_maddr_rlock()/if_maddr_runlock() rather than IF_ADDR_LOCK()/
IF_ADDR_UNLOCK() across network device drivers when accessing the
per-interface multicast address list, if_multiaddrs. This will
allow us to change the locking strategy without affecting our driver
programming interface or binary interface.

For two wireless drivers, remove unnecessary locking, since they
don't actually access the multicast address list.

Approved by: re (kib)
MFC after: 6 weeks

Fix shutdown prototypes.

Clean out some empty mergeinfo records, presumably by people doing local
cp/mv operations. The full repo-relative URL should be specified for the
source in these cases.

Move the tl driver form sys/pci to sys/dev/tl.