uboot: (firmwareOdroidC2/C4) don't invoke patch tool, use patches = [] instead

https://github.com/NixOS/nixpkgs/blob/master/pkgs/stdenv/generic/setup.sh#L948
this can do it nicely.

Signed-off-by: Anton Arapov <anton@deadbeef.mx>

pkgs/os-specific/linux/rtl8821au/default.nix

@@ -0,0 +1,46 @@
+{ lib, stdenv, fetchFromGitHub, kernel, bc, nukeReferences }:
+
+stdenv.mkDerivation rec {
+  pname = "rtl8821au";
+  version = "${kernel.version}-unstable-2022-03-08";
+
+  src = fetchFromGitHub {
+    owner = "morrownr";
+    repo = "8821au-20210708";
+    rev = "2c0c6fef81c0c7dcf8fa06fc4ab72168abc4f7bb";
+    sha256 = "sha256-Hdzi3pGqH71O0Jenjd/myG4+rZDLC/CcWHkjDoXBxS0=";
+  };
+
+  nativeBuildInputs = [ bc nukeReferences ];
+  buildInputs = kernel.moduleBuildDependencies;
+
+  hardeningDisable = [ "pic" "format" ];
+
+  NIX_CFLAGS_COMPILE="-Wno-error=incompatible-pointer-types";
+
+  prePatch = ''
+    substituteInPlace ./Makefile \
+      --replace /lib/modules/ "${kernel.dev}/lib/modules/" \
+      --replace '$(shell uname -r)' "${kernel.modDirVersion}" \
+      --replace /sbin/depmod \# \
+      --replace '$(MODDESTDIR)' "$out/lib/modules/${kernel.modDirVersion}/kernel/net/wireless/"
+  '';
+
+  preInstall = ''
+    mkdir -p "$out/lib/modules/${kernel.modDirVersion}/kernel/net/wireless/"
+  '';
+
+  postInstall = ''
+    nuke-refs $out/lib/modules/*/kernel/net/wireless/*.ko
+  '';
+
+  enableParallelBuilding = true;
+
+  meta = with lib; {
+    description = "rtl8821AU and rtl8812AU chipset driver with firmware";
+    homepage = "https://github.com/morrownr/8821au";
+    license = licenses.gpl2Only;
+    platforms = [ "x86_64-linux" "i686-linux" ];
+    maintainers = with maintainers; [ plchldr ];
+  };
+}