rtc: rtd119x: Fix format of SPDX identifier

For C files, use the C99 format (//).

Signed-off-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20210707075804.337458-7-nobuhiro1.iwamatsu@toshiba.co.jp

drivers/rtc/rtc-rtd119x.c

+// SPDX-License-Identifier: GPL-2.0+
 /*
  * Realtek RTD129x RTC
  *
  * Copyright (c) 2017 Andreas Färber
- *
- * SPDX-License-Identifier: GPL-2.0+
  */
 
 #include <linux/clk.h>