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/tools/nix/nixos-generators/default.nix

@@ -0,0 +1,27 @@
+{ stdenv, lib, fetchFromGitHub, makeWrapper, coreutils, jq, findutils, nix  }:
+
+stdenv.mkDerivation rec {
+  pname = "nixos-generators";
+  version = "1.6.0";
+  src = fetchFromGitHub {
+    owner = "nix-community";
+    repo = "nixos-generators";
+    rev = version;
+    sha256 = "sha256-dpim9Mtd57Yj6qt7p7UKwjWm6NnOU3S7jaEyEscSyPE=";
+  };
+  nativeBuildInputs = [ makeWrapper ];
+  installFlags = [ "PREFIX=$(out)" ];
+  postFixup = ''
+    wrapProgram $out/bin/nixos-generate \
+      --prefix PATH : ${lib.makeBinPath [ jq coreutils findutils nix ] }
+  '';
+
+  meta = with lib; {
+    description = "Collection of image builders";
+    homepage    = "https://github.com/nix-community/nixos-generators";
+    license     = licenses.mit;
+    maintainers = with maintainers; [ lassulus ];
+    mainProgram = "nixos-generate";
+    platforms   = platforms.unix;
+  };
+}