Adjust R64, RP64 and PBP to use Tow-Boot and drop temp/arm-trusted-firmware

CC device maintainers:

• RP64: @flacks, @PureTryOut
• PBP: @craftyguy, (not listed as maintainer: @MartijnBraam)
• R64: @tvall

Let's adjust the device ports to use tow-boot, similar to how we did it with the pinephone pro: https://postmarketos.org/edge/2022/03/28/ppp-tow-boot/

Besides the nice things that Tow-Boot has, this will allow us to get rid of temp/arm-trusted-firmware in pmaports. We can't add rk3399 and rk3328 platforms to main/arm-trusted-firmware in alpine, because it requires community/gcc-arm-none-eabi (packages from main can't depend on ones from community). Moving arm-trusted-firmware to community is also not possible, because main/u-boot depends on it and this needs to stay in main.

TODO:

• adjust rock64
  • packaging
  • wiki
  • write edge post
• adjust rockpro64
  • packaging
  • wiki
  • write edge post
• adjust pinebookpro
  • packaging
  • wiki
  • write edge post
• check if pmaports arm-trusted-firmware is in sync with alpine's arm-trusted-firmware, adjust alpine pkg if needed
• drop temp/arm-trusted-firmware
• bonus points for figuring out an upgrade path that doesn't require reinstall

EDIT: added todo list and R64