watchdog: it87: Use infrastructure to stop watchdog on reboot

Use watchdog_stop_on_reboot() to stop the watchdog on reboot instead
of registering a driver-specific notifier.

While at it, reorder remaining include files alphabetically.

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