Compiling U-boot mainline for RK3399Pro (Radxa Rock Pi N10)

It's always important to maintain the bootloader up-to-date in the case of ARMv8-based SBCs. Changes are always coming to the ATF, even the DRAM initialization firmware routines, and of course to U-boot itself. Since the process is not always straightforward, I decided to drop some notes on my particular wrestle with compiling U-boot for Radxa Rock Pi N10 RK3399pro-based SBC. Personally the…