This version is patched so that:
* ELF and API features are enabled.
* The default environment is trimmed to just what's needed to boot.
* The saveenv command writes to the file u-boot.env on the FAT partition.
* The DTB file name is chosen based on the board model and passed to ubldr
using the fdtfile env variable. ubldr loads the DTB from /boot/dtb/ on
the FreeBSD partition.
* By default, it loads ELF ubldr from file ubldr on the FAT partition to
address 0x42000000, and launches it.
For information about running FreeBSD on Allwinner SoCs, see
https://wiki.freebsd.org/FreeBSD/arm/Allwinner
Differential Revision: https://reviews.freebsd.org/D2874
Reviewed by: garga
Approved by: garga
ae95160278