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/development/beam-modules/build-hex.nix

@@ -0,0 +1,20 @@
+{ lib, buildRebar3, fetchHex }:
+
+{ name, version, sha256
+, builder ? buildRebar3
+, hexPkg ? name
+, ... }@attrs:
+
+with lib;
+
+let
+  pkg = self: builder (attrs // {
+
+    src = fetchHex {
+      pkg = hexPkg;
+      inherit version;
+      inherit sha256;
+    };
+  });
+in
+  fix pkg