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>

lib/tests/modules/define-attrsOfSub-foo-if-enable.nix

@@ -0,0 +1,7 @@
+{ config, lib, ... }:
+
+{
+  attrsOfSub.foo = lib.mkIf config.enable {
+    enable = true;
+  };
+}