U-Boot loader and related files for the Pine64 RockPro64.

To install this bootloader on an sdcard just do:
dd if=/usr/local/share/u-boot/u-boot-rockpro64/idbloader.img of=/path/to/sdcarddevice seek=64 bs=512 conv=sync
dd if=/usr/local/share/u-boot/u-boot-rockpro64/u-boot.itb of=/path/to/sdcarddevice seek=16384 bs=512 conv=sync