If we need to restart the watchdog due to someone changing the timeout
interval, stop the watchdog before restarting it.  Otherwise, the new
timeout doesn't seem to take.

Signed-off-by: Andrew Chew <achew@nvidia.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>