Backport a (yet unmerged) patch that allows NixOS to boot correctly on new Pi4 boards using the BCM2711C0 SoC. Revert this when the patch is available in mainline U-Boot.

A precompiled binary is available here: https://static.0upti.me/pi4/ if anyone wants to test - just drop it into your firmware partition.

To easily reproduce the build locally, use this Nix expression:

{ pkgs ? import <nixpkgs> { } }:
pkgs.ubootRaspberryPi4_64bit.overrideAttrs (old: {
  patches = old.patches ++ [
    (pkgs.fetchpatch {
      url = "https://patchwork.ozlabs.org/series/259129/mbox/";
      sha256 = "04x55a62a5p4mv0ddpx7dnsh5pnx46vibnq8cry7hgwf4krl64gl";
    })
  ];
})

(save it to uboot.nix, then nix-build uboot.nix, the final binary will be in result/, drop it into the firmware partition and rename to u-boot-rpi4.bin)

NB: to cross-compile from a desktop, use pkgs.pkgsCross.aarch64-multiplatform.ubootRaspberryPi4_64bit instead of pkgs.ubootRaspberryPi4_64bit.

Motivation for this change

See #135828

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• 21.11 Release Notes (or backporting 21.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.