of: Use SPDX license tag for DT files

Convert remaining DT files to use SPDX-License-Identifier tags.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
Reviewed-by: Frank Rowand <frank.rowand@sony.com>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Signed-off-by: Rob Herring <robh@kernel.org>

drivers/of/base.c

@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0+
 /*
  * Procedures for creating, accessing and interpreting the device tree.
  *
@@ -11,11 +12,6 @@
  *
  *  Reconsolidated from arch/x/kernel/prom.c by Stephen Rothwell and
  *  Grant Likely.
- *
- *      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; either version
- *      2 of the License, or (at your option) any later version.
  */
 
 #define pr_fmt(fmt)	"OF: " fmt