rtc: convert core to SPDX identifier

Use SPDX-License-Identifier instead of a verbose license text. Also fix the
block comment alignment.
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/class.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * RTC subsystem, base class
  *
@@ -5,11 +6,7 @@
  * Author: Alessandro Zummo <a.zummo@towertech.it>
  *
  * class skeleton from drivers/hwmon/hwmon.c
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
-*/
+ */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 

drivers/rtc/dev.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * RTC subsystem, dev interface
  *
@@ -5,11 +6,7 @@
  * Author: Alessandro Zummo <a.zummo@towertech.it>
  *
  * based on arch/arm/common/rtctime.c
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
-*/
+ */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 

drivers/rtc/hctosys.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * RTC subsystem, initialize system time on startup
  *
  * Copyright (C) 2005 Tower Technologies
  * Author: Alessandro Zummo <a.zummo@towertech.it>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
-*/
+ */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 

drivers/rtc/interface.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * RTC subsystem, interface functions
  *
@@ -5,11 +6,7 @@
  * Author: Alessandro Zummo <a.zummo@towertech.it>
  *
  * based on arch/arm/common/rtctime.c
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
-*/
+ */
 
 #include <linux/rtc.h>
 #include <linux/sched.h>

drivers/rtc/lib.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * rtc and date/time utility functions
  *
@@ -5,11 +6,7 @@
  * Author: Alessandro Zummo <a.zummo@towertech.it>
  *
  * based on arch/arm/common/rtctime.c and other bits
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
-*/
+ */
 
 #include <linux/export.h>
 #include <linux/rtc.h>

drivers/rtc/nvmem.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * RTC subsystem, nvmem interface
  *
  * Copyright (C) 2017 Alexandre Belloni
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
  */
 
 #include <linux/err.h>

drivers/rtc/proc.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * RTC subsystem, proc interface
  *
@@ -5,11 +6,7 @@
  * Author: Alessandro Zummo <a.zummo@towertech.it>
  *
  * based on arch/arm/common/rtctime.c
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
-*/
+ */
 
 #include <linux/module.h>
 #include <linux/rtc.h>

drivers/rtc/sysfs.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * RTC subsystem, sysfs interface
  *
  * Copyright (C) 2005 Tower Technologies
  * Author: Alessandro Zummo <a.zummo@towertech.it>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
-*/
+ */
 
 #include <linux/module.h>
 #include <linux/rtc.h>

drivers/rtc/systohc.c

-/*
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published by
- * the Free Software Foundation.
- *
- */
+// SPDX-License-Identifier: GPL-2.0
 #include <linux/rtc.h>
 #include <linux/time.h>