memory: pl172: Add GPLv2 SPDX license header

Add GPLv2 license header and remove GPL boiler plate text.
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

drivers/memory/pl172.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Memory controller driver for ARM PrimeCell PL172
  * PrimeCell MultiPort Memory Controller (PL172)
@@ -6,10 +7,6 @@
  *
  * Based on:
  * TI AEMIF driver, Copyright (C) 2010 - 2013 Texas Instruments Inc.
- *
- * 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/amba/bus.h>