U-Boot loader and related files for the OrangePi PC

To install this bootloader on an sdcard just do :
dd if=$LOCALBASE/share/u-boot/u-boot-orangepi-pc/u-boot-sunxi-with-spl.bin of=/path/to/sdcarddevice bs=1k seek=8 conv=sync

This version is patched so that:
 * API features are enabled.
 * A boot.scr (U-Boot script) that loads ubldr.bin and execute it is included

For information about running FreeBSD on Allwinner boards, see
https://wiki.freebsd.org/FreeBSD/arm/Allwinner
