* Switched rockchip64/rk3399 to u-boot v2020.10
* Some tweaks for SPI booting on ROCK Pi 4 in u-boot v2020.10
* Adjusted NanoPi M4V2 config for u-boot v2020.10
* Disabled PREBOOT for RockPro64 in u-boot v2020.10
It breaks boot during fdt loading
* Fix issues with booting from SPI flash for RockPro64
* Moved NanoPi R4S patches to board specific folder
