watchdog: tangox: Mark running watchdog correctly

A running watchdog is marked with WDOG_HW_RUNNING, not with WDOG_ACTIVE.
WDOG_ACTIVE indicates that the watchdog device has been opened from user
space.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>