fix u-boot build

fix u-boot build

cleanup inputs

flake.lock: Update

Flake lock file updates:

• Updated input 'uboot-vf2-src':
    'github:misuzu/u-boot/2e3feb5fbac891e105c521aa479ccbf59c04903f' (2023-11-21)
  → 'github:misuzu/u-boot/923e0dcf7d5040f65e63b67464a1b64bd4e8cbff' (2023-12-06)

flake.lock: Update

Flake lock file updates:

• Updated input 'uboot-vf2-src':
    'github:misuzu/u-boot/056c05606e0a6f3a1275563a003c8c19f58ef5ed' (2023-08-12)
  → 'github:misuzu/u-boot/0850e3a5b9d02cc5d9c06dbd22e97a16c67285e8' (2023-08-16)

expose firmware packages

update firmware-vf2-vendor

use upstream nixpkgs for native

Update README.md