MFC r284683:
Enable ttyu1, ttyu2, ttyu3 for arm installations.

This should make all consoles available, whether it
is VGA, HDMI, serial, or JTAG, but more importantly
enables all consoles when ttyu0 is not predictable.
For example, the Pandaboard ES apparently has three
consoles available, but the DB9/RS232 serial port is
ttyu2, so not available by default after the system
boots.

Sponsored by: The FreeBSD Foundation

MFC r282500, r282693:
r282500:
Add initial support for building RPI2 images.

In release.sh, allow overriding buildenv_setup() before
the handoff to arm/release.sh.

Copy arm/RPI-B.conf -> arm/RPI2.conf, set UBOOT_PORT and
the correct KERNEL, and add the buildenv_setup() override
to install the sysutils/u-boot-rpi2 port/package.

Copy tools/arm/crochet-RPI-B.conf -> tools/arm/crochet-RPI2.conf,
and set the correct entries for the RaspberryPi2 board.

r282693:
Merge ^/projects/release-arm-redux into ^/head.

Of note:

- This commit adds native FreeBSD/arm release build support without
requiring out-of-tree utilities.

- Part of this merge removes the WANDBOARD-{SOLO,DUAL,QUAD} kernel
configuration files, for which the IMX6 kernel configuration file
should be used instead.

- The resulting images have a 'freebsd' user (password 'freebsd'),
to allow ssh(1) access when console access is not available (VGA
or serial). The default 'root' user password is set to 'root'.

- The /etc/ttys file for arm images now enable both ttyv0 and ttyu0
by default.

Note: The RPI2 kernel configuration does not yet exist in stable/10,
however the merge conflicts needed to be properly resolved.
Additionally, SRCBRANCH has been set to base/stable/10 in the updated
arm configuration files as part of this commit.

Sponsored by: The FreeBSD Foundation

MFC r284683:
Enable ttyu1, ttyu2, ttyu3 for arm installations.

This should make all consoles available, whether it
is VGA, HDMI, serial, or JTAG, but more importantly
enables all consoles when ttyu0 is not predictable.
For example, the Pandaboard ES apparently has three
consoles available, but the DB9/RS232 serial port is
ttyu2, so not available by default after the system
boots.

Sponsored by: The FreeBSD Foundation

MFC r282500, r282693:
r282500:
Add initial support for building RPI2 images.

In release.sh, allow overriding buildenv_setup() before
the handoff to arm/release.sh.

Copy arm/RPI-B.conf -> arm/RPI2.conf, set UBOOT_PORT and
the correct KERNEL, and add the buildenv_setup() override
to install the sysutils/u-boot-rpi2 port/package.

Copy tools/arm/crochet-RPI-B.conf -> tools/arm/crochet-RPI2.conf,
and set the correct entries for the RaspberryPi2 board.

r282693:
Merge ^/projects/release-arm-redux into ^/head.

Of note:

- This commit adds native FreeBSD/arm release build support without
requiring out-of-tree utilities.

- Part of this merge removes the WANDBOARD-{SOLO,DUAL,QUAD} kernel
configuration files, for which the IMX6 kernel configuration file
should be used instead.

- The resulting images have a 'freebsd' user (password 'freebsd'),
to allow ssh(1) access when console access is not available (VGA
or serial). The default 'root' user password is set to 'root'.

- The /etc/ttys file for arm images now enable both ttyv0 and ttyu0
by default.

Note: The RPI2 kernel configuration does not yet exist in stable/10,
however the merge conflicts needed to be properly resolved.
Additionally, SRCBRANCH has been set to base/stable/10 in the updated
arm configuration files as part of this commit.

Sponsored by: The FreeBSD Foundation