watchdog: orion_wdt: Mark watchdog as active when running at probe

If the watchdog is fully enabled and running at probe,
mark it as such so the watchdog core can handle it until
the watchdog device is opened.

Signed-off-by: Maxim Kochetkov <fido_max@inbox.ru>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
[groeck: Updated subject and description]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>