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>

nixos/modules/security/rngd.nix

@@ -0,0 +1,16 @@
+{ lib, ... }:
+let
+  removed = k: lib.mkRemovedOptionModule [ "security" "rngd" k ];
+in
+{
+  imports = [
+    (removed "enable" ''
+       rngd is not necessary for any device that the kernel recognises
+       as an hardware RNG, as it will automatically run the krngd task
+       to periodically collect random data from the device and mix it
+       into the kernel's RNG.
+    '')
+    (removed "debug"
+      "The rngd module was removed, so its debug option does nothing.")
+  ];
+}