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/profiles/headless.nix

@@ -0,0 +1,25 @@
+# Common configuration for headless machines (e.g., Amazon EC2
+# instances).
+
+{ lib, ... }:
+
+with lib;
+
+{
+  boot.vesa = false;
+
+  # Don't start a tty on the serial consoles.
+  systemd.services."serial-getty@ttyS0".enable = lib.mkDefault false;
+  systemd.services."serial-getty@hvc0".enable = false;
+  systemd.services."getty@tty1".enable = false;
+  systemd.services."autovt@".enable = false;
+
+  # Since we can't manually respond to a panic, just reboot.
+  boot.kernelParams = [ "panic=1" "boot.panic_on_fail" ];
+
+  # Don't allow emergency mode, because we don't have a console.
+  systemd.enableEmergencyMode = false;
+
+  # Being headless, we don't need a GRUB splash image.
+  boot.loader.grub.splashImage = null;
+}