Fixing U-boot to support boot from NVMEs

ROCK 4 Series
19

Hey @Human_USB

I have tested 2 serial USB:

  1. CH340 based (like here) + good quality dupont cable.
  2. USB TTL debug cable found on AllNet store.

More info here:

and here:
https://wiki.radxa.com/Rockpi4/dev/serial-console