watchdog: at91sam9: request the irq with IRQF_NO_SUSPEND

The watchdog interrupt (only used when activating software watchdog)
shouldn't be suspended when entering suspend mode, because it is shared
with a timer device (which request the line with IRQF_NO_SUSPEND) and once
the watchdog "Mode Register" has been written, it cannot be changed (which
means we cannot disable the watchdog interrupt when entering suspend).

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Reviewed-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>