U-Boot loader and related files for the Nanopi R2S.

To install this bootloader on an sdcard just do:
dd if=/usr/local/share/u-boot/u-boot-nanopi-r2s/idbloader.img of=/path/to/sdcarddevice seek=64 bs=512 conv=sync
dd if=/usr/local/share/u-boot/u-boot-nanopi-r2s/u-boot.itb of=/path/to/sdcarddevice seek=16384 bs=512 conv=sync