watchdog: convert remaining drivers to use SPDX license identifier

This gets rid of the unnecessary license boilerplate, and avoids
having to deal with individual patches one by one.

No functional changes.

Reviewed-by: Jerry Hoemann <jerry.hoemann@hpe.com>
Acked-by: Sylvain Lemieux <slemieux.tyco@gmail.com>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

drivers/watchdog/acquirewdt.c

@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0+
 /*
  *	Acquire Single Board Computer Watchdog Timer driver
  *
@@ -6,11 +7,6 @@
  *	(c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
  *						All Rights Reserved.
  *
- *	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; either version
- *	2 of the License, or (at your option) any later version.
- *
  *	Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
  *	warranty for any of this software. This material is provided
  *	"AS-IS" and at no charge.