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/fetchdocker/fetchDockerLayer.nix

@@ -0,0 +1,13 @@
+pkgargs@{ stdenv, lib, haskellPackages, writeText, gawk }:
+let
+  generic-fetcher =
+    import ./generic-fetcher.nix pkgargs;
+in
+
+args@{ layerDigest, ... }:
+
+generic-fetcher ({
+  fetcher = "hocker-layer";
+  name    = "docker-layer-${layerDigest}.tar.gz";
+  tag     = "unused";
+} // args)