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/substitute/substitute.nix

@@ -0,0 +1,14 @@
+{ stdenvNoCC }:
+
+args:
+
+# This is a wrapper around `substitute` in the stdenv.
+# The `replacements` attribute should be a list of list of arguments
+# to `substitute`, such as `[ "--replace" "sourcetext" "replacementtext" ]`
+stdenvNoCC.mkDerivation ({
+  name = if args ? name then args.name else baseNameOf (toString args.src);
+  builder = ./substitute.sh;
+  inherit (args) src;
+  preferLocalBuild = true;
+  allowSubstitutes = false;
+} // args // { replacements = args.replacements; })