Log Message:
update u-boot for rockpro64 and pinebook-pro to u-boot 2021.07.

- adds support for panel on pinebook-pro (needs rk_anxdp.c r1.4)
- enable ahci/sata for rockpro64
- workaround usb_stop() bug in u-boot.  see eg:
  \ 
https://patchwork.ozlabs.org/project/uboot/patch/20210406151059.1187379-1-icenowy@aosc.io/
- remove long obsolete files

tested on original iso pbp that was upgraded to ansi key, and a
first generation ansi pbp, as well as two rockpro64 v2.1s.