rtc: imxdi: convert to SPDX identifier

Use SPDX-License-Identifier instead of a verbose license text.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/rtc-imxdi.c

+// SPDX-License-Identifier: GPL-2.0+
 /*
  * Copyright 2008-2009 Freescale Semiconductor, Inc. All Rights Reserved.
  * Copyright 2010 Orex Computed Radiography
  */
 
-/*
- * 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
- */
-
-/* based on rtc-mc13892.c */
-
 /*
  * This driver uses the 47-bit 32 kHz counter in the Freescale DryIce block
  * to implement a Linux RTC. Times and alarms are truncated to seconds.