rtc: 88pm80x: 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-88pm80x.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Real Time Clock driver for Marvell 88PM80x PMIC
  *
  * Copyright (c) 2012 Marvell International Ltd.
  *  Wenzeng Chen<wzch@marvell.com>
  *  Qiao Zhou <zhouqiao@marvell.com>
- *
- * This file is subject to the terms and conditions of the GNU General
- * Public License. See the file "COPYING" in the main directory of this
- * archive for more details.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; 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/kernel.h>