rtc: jz4740: convert to SPDX identifier

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

drivers/rtc/rtc-jz4740.c

+// SPDX-License-Identifier: GPL-2.0+
 /*
  *  Copyright (C) 2009-2010, Lars-Peter Clausen <lars@metafoo.de>
  *  Copyright (C) 2010, Paul Cercueil <paul@crapouillou.net>
  *	 JZ4740 SoC RTC driver
- *
- *  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.
- *
- *  You should have received a copy of the GNU General Public License along
- *  with this program; if not, write to the Free Software Foundation, Inc.,
- *  675 Mass Ave, Cambridge, MA 02139, USA.
- *
  */
 
 #include <linux/clk.h>