watchdog: iTCO-wdt: handle 5th variation for Apollo Lake

The Apollo Lake Watchdog has the no_reboot flag in the 4th bit.

Signed-off-by: Yong, Jonathan <jonathan.yong@intel.com>
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>