rtc: tps6586x: convert to SPDX identifier

Use SPDX-License-Identifier instead of a verbose license text.
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/20210707075804.337458-9-nobuhiro1.iwamatsu@toshiba.co.jp

drivers/rtc/rtc-tps6586x.c

+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * rtc-tps6586x.c: RTC driver for TI PMIC TPS6586X
  *
  * Copyright (c) 2012, NVIDIA Corporation.
  *
  * Author: Laxman Dewangan <ldewangan@nvidia.com>
- *
- * 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 version 2.
- *
- * This program is distributed "as is" WITHOUT ANY WARRANTY of any kind,
- * whether express or implied; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * General Public License for more details.
- *
- * 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., 59 Temple Place, Suite 330, Boston, MA
- * 02111-1307, USA
  */
 
 #include <linux/device.h>