watchdog: add driver for the MEN 16z069 IP-Core

Add a driver for the MEN 16z069 Watchdog and Reset Controller IP-Core.

Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Michael Moese <mmoese@suse.de>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>