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/tools/package-management/nix-update-source/default.nix

@@ -0,0 +1,58 @@
+{ lib, pkgs, fetchFromGitHub, python3Packages, nix-prefetch-scripts, runtimeShell }:
+
+python3Packages.buildPythonApplication rec {
+  pname = "nix-update-source";
+  version = "0.6.3";
+
+  src = fetchFromGitHub {
+    owner = "timbertson";
+    repo = "nix-update-source";
+    rev = "version-${version}";
+    sha256 = "157wvv9vnaszzwbj68jpdc0imcm1hdab3z760bx2axbsgfpqqilz";
+  };
+
+  propagatedBuildInputs = [ nix-prefetch-scripts ];
+
+  doCheck = false;
+
+  passthru = {
+    # NOTE: `fetch` should not be used within nixpkgs because it
+    # uses a non-idiomatic structure. It is provided for use by
+    # out-of-tree nix derivations.
+    fetch = path:
+      let
+        fetchers = {
+          # whitelist of allowed fetchers
+          inherit (pkgs) fetchgit fetchurl fetchFromGitHub;
+        };
+        json = lib.importJSON path;
+        fetchFn = builtins.getAttr json.fetch.fn fetchers;
+        src = fetchFn json.fetch.args;
+      in
+      json // json.fetch // {
+        inherit src;
+        overrideSrc = drv: lib.overrideDerivation drv (orig: { inherit src; });
+      };
+
+    updateScript = ''
+      #!${runtimeShell}
+      set -e
+      echo
+      cd ${toString ./.}
+      ${pkgs.nix-update-source}/bin/nix-update-source \
+        --prompt version \
+        --replace-attr version \
+        --set owner timbertson \
+        --set repo nix-update-source \
+        --set type fetchFromGitHub \
+        --set rev 'version-{version}' \
+        --modify-nix default.nix
+    '';
+  };
+
+  meta = {
+    description = "Utility to automate updating of nix derivation sources";
+    maintainers = with lib.maintainers; [ timbertson ];
+    license = lib.licenses.mit;
+  };
+}