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/tasks/powertop.nix

@@ -0,0 +1,29 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.powerManagement.powertop;
+in {
+  ###### interface
+
+  options.powerManagement.powertop.enable = mkEnableOption "powertop auto tuning on startup";
+
+  ###### implementation
+
+  config = mkIf (cfg.enable) {
+    systemd.services = {
+      powertop = {
+        wantedBy = [ "multi-user.target" ];
+        after = [ "multi-user.target" ];
+        description = "Powertop tunings";
+        path = [ pkgs.kmod ];
+        serviceConfig = {
+          Type = "oneshot";
+          RemainAfterExit = "yes";
+          ExecStart = "${pkgs.powertop}/bin/powertop --auto-tune";
+        };
+      };
+    };
+  };
+}