watchdog: intel-mid_wdt: Keep watchdog running

Firmware followed by bootloader leaves watchdog running.

Keep it running in the driver.

User will not need any additional options to reboot in case of panic
during boot.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.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>