rtc: ab3100: convert to SPDX identifier

Use SPDX-License-Identifier instead of the custom license line.

Reviewed-by: Linus Walleij <[e-mail]>
Signed-off-by: Alexandre Belloni <[e-mail]>

drivers/rtc/rtc-ab3100.c

···
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2007-2009 ST-Ericsson AB
- * License terms: GNU General Public License (GPL) version 2
  * RTC clock driver for the AB3100 Analog Baseband Chip
  * Author: Linus Walleij <[e-mail]>
  */