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/build-support/docker/nix-prefetch-docker.nix

@@ -0,0 +1,24 @@
+{ lib, stdenv, makeWrapper, nix, skopeo, jq }:
+
+stdenv.mkDerivation {
+  name = "nix-prefetch-docker";
+
+  nativeBuildInputs = [ makeWrapper ];
+
+  dontUnpack = true;
+
+  installPhase = ''
+    install -vD ${./nix-prefetch-docker} $out/bin/$name;
+    wrapProgram $out/bin/$name \
+      --prefix PATH : ${lib.makeBinPath [ nix skopeo jq ]} \
+      --set HOME /homeless-shelter
+  '';
+
+  preferLocalBuild = true;
+
+  meta = with lib; {
+    description = "Script used to obtain source hashes for dockerTools.pullImage";
+    maintainers = with maintainers; [ offline ];
+    platforms = platforms.unix;
+  };
+}