watchdog: iTCO_wdt: Replace shutdown function with call to watchdog_stop_on_reboot

watchdog: iTCO_wdt: Replace shutdown function with call to watchdog_stop_on_reboot

The shutdown function calls the stop function.
Call watchdog_stop_on_reboot() from probe instead.

The conversion was done automatically with coccinelle using the
following semantic patches. The semantic patches and the scripts used
to generate this commit log are available at
https://github.com/groeck/coccinelle-patches

- Replace shutdown function with call to watchdog_stop_on_reboot()

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>