ARM: berlin: switch to SPDX license identifier

Use the appropriate SPDX license identifier and drop the previous
boilerplate license text.

Signed-off-by: Jisheng Zhang <[e-mail]>

arch/arm/mach-berlin/berlin.c

···
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Device Tree support for Marvell Berlin SoCs.
  *
···
  *
  * based on GPL'ed 2.6 kernel sources
  *  (c) Marvell International Ltd.
- *
- * This file is licensed under the terms of the GNU General Public
- * License version 2.  This program is licensed "as is" without any
- * warranty of any kind, whether express or implied.
  */
 
 #include <linux/init.h>

arch/arm/mach-berlin/headsmp.S

···
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2014 Marvell Technology Group Ltd.
  *
  * Antoine Ténart <[e-mail]>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
  */
 
 #include <linux/linkage.h>

arch/arm/mach-berlin/platsmp.c

···
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2014 Marvell Technology Group Ltd.
  *
  * Antoine Ténart <[e-mail]>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
  */
 
 #include <linux/io.h>