watchdog: add SPDX identifiers for watchdog subsystem

- Add SPDX identifier
- Remove boiler plate license text
- If MODULE_LICENSE and boiler plate does not match, go for boiler plate
  license

Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
Acked-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Acked-by: Baruch Siach <baruch@tkos.co.il>
Acked-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Acked-by: Keiji Hayashibara <hayashibara.keiji@socionext.com>
Acked-by: Johannes Thumshirn <jth@kernel.org>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Mans Rullgard <mans@mansr.com>
Acked-by: Matthias Brugger <matthias.bgg@gmail.com>
Acked-by: Michal Simek <michal.simek@xilinx.com>
Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Acked-by: Tomas Winkler <tomas.winkler@intel.com>
Acked-by: Patrice Chotard <patrice.chotard@st.com>
Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

drivers/watchdog/at91sam9_wdt.c

@@ -1,12 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0+
 /*
  * Watchdog driver for Atmel AT91SAM9x processors.
  *
  * Copyright (C) 2008 Renaud CERRATO r.cerrato@til-technologies.fr
  *
- * 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.
  */
 
 /*