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/system/boot/shutdown.nix

@@ -0,0 +1,27 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+{
+
+  # This unit saves the value of the system clock to the hardware
+  # clock on shutdown.
+  systemd.services.save-hwclock =
+    { description = "Save Hardware Clock";
+
+      wantedBy = [ "shutdown.target" ];
+
+      unitConfig = {
+        DefaultDependencies = false;
+        ConditionPathExists = "/dev/rtc";
+      };
+
+      serviceConfig = {
+        Type = "oneshot";
+        ExecStart = "${pkgs.util-linux}/sbin/hwclock --systohc ${if config.time.hardwareClockInLocalTime then "--localtime" else "--utc"}";
+      };
+    };
+
+  boot.kernel.sysctl."kernel.poweroff_cmd" = "${config.systemd.package}/sbin/poweroff";
+
+}