ARM: dts: lpc32xx: use SPDX license identifier

Replace GPLv2+ header with the SPDX identifier.
Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>

arch/arm/boot/dts/lpc32xx.dtsi

+// SPDX-License-Identifier: GPL-2.0+
 /*
  * NXP LPC32xx SoC
  *
  * Copyright (C) 2015-2019 Vladimir Zapolskiy <vz@mleia.com>
  * Copyright 2012 Roland Stigge <stigge@antcom.de>
- *
- * The code contained herein is licensed under the GNU General Public
- * License. You may obtain a copy of the GNU General Public License
- * Version 2 or later at the following locations:
- *
- * http://www.opensource.org/licenses/gpl-license.html
- * http://www.gnu.org/copyleft/gpl.html
  */
 
 #include <dt-bindings/clock/lpc32xx-clock.h>