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/fetchcvs/default.nix

@@ -0,0 +1,20 @@
+# example tags:
+# date="2007-20-10"; (get the last version before given date)
+# tag="<tagname>" (get version by tag name)
+# If you don't specify neither one date="NOW" will be used (get latest)
+
+{stdenvNoCC, cvs, openssh}:
+
+{cvsRoot, module, tag ? null, date ? null, sha256}:
+
+stdenvNoCC.mkDerivation {
+  name = "cvs-export";
+  builder = ./builder.sh;
+  nativeBuildInputs = [cvs openssh];
+
+  outputHashAlgo = "sha256";
+  outputHashMode = "recursive";
+  outputHash = sha256;
+
+  inherit cvsRoot module sha256 tag date;
+}