mainboard/google/gru: Add license header to memlayout.ld

I missed this license header, and it's causing a build breakage.

Change-Id: If472e5c081bd282f0b482af629d6ec2314a2c329
Signed-off-by: Martin Roth <martinroth@google.com>
Reviewed-on: https://review.coreboot.org/14388
Reviewed-by: David Hendricks <dhendrix@chromium.org>
Tested-by: build bot (Jenkins)

src/mainboard/google/gru/memlayout.ld

@@ -1 +1,16 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2016 Rockchip Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
  #include <soc/memlayout.ld>