- Copy stable/10@296371 to releng/10.3 in preparation for 10.3-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.3.
- Update default pkg(8) configuration to use the quarterly branch.

Approved by: re (implicit)

MFC r268836: Fix a typo in a gpio node name.

MFC r271097, r271100, r271101, r271102, r271124:

- Add a basic iomux driver for imx6.
- Implement the same public interface in imx51 and imx6 iomux
- The iomux driver is no longer optional, remove it from kernel configs.
- Implement the imx_iomux_get/set_gpr() interface for imx6.
- Stop setting the iomux device status to disabled, now that we have a driver.

MFC r268834, r268835:

o Enable GPIO device driver for i.MX6.
It was originally written for i.MX5 and compatible with newer chip.
o Extend device tree information
o style(9) fixes
o Rename gpio driver file.

MFC 262614, 262625, 262626, 262627, 262682, 262714, 262725, 262736

Integrate device-tree upstream files into the build process:
(1) Invoke cpp to bring in files via #include (although the old
/include/ stuff is supported still).
(2) bring in files from either vendor tree or freebsd-custom files
when building.
(3) move all dts* files from sys/boot/fdt/dts to
sys/boot/fdt/dts/${MACHINE} as appropriate.
(4) encode all the magic to do the build in sys/tools/fdt/make_dtb.sh
so that the different places in the tree use the exact same logic.
(5) switch back to gpl dtc by default. the bsdl one in the tree has
significant issues not easily addressed by those unfamiliar with
the code.

Only try to build the static dtb when we're building a static dtb.

Use proper include path for dtc as well as cpp.

Fix syntax errors (missing ; other minor glitches) in existing dts files.

Integrate device-tree upstream files into the build process:
(1) Invoke cpp to bring in files via #include (although the old
/include/ stuff is supported still).
(2) bring in files from either vendor tree or freebsd-custom files
when building.
(3) move all dts* files from sys/boot/fdt/dts to
sys/boot/fdt/dts/${MACHINE} as appropriate.
(4) encode all the magic to do the build in sys/tools/fdt/make_dtb.sh
so that the different places in the tree use the exact same logic.
(5) switch back to gpl dtc by default. the bsdl one in the tree has
significant issues not easily addressed by those unfamiliar with
the code.

Enable both sdcard slots, but not the sdio-based wifi that we don't yet
have a driver for.

Add dts source for imx6 SoCs and for Wandboard boards.

The imx6.dtsi is incomplete, but has enough to support devices that work
right now. Eventually it will need to be split into several files that
account for the differences between SoCs in the imx6 family.

The board config for Wandboard Dual is untested. Solo and Quad work, but
one one core is turned on for the quad right now (baby steps).