watchdog: f71808e_wdt: Add F81803 support

This adds watchdog support for the Fintek F81803 Super I/O chip.

Testing was done on the Seneca XK-QUAD.

Signed-off-by: Jaret Cantu <jaret.cantu@timesys.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20190912175550.9340-1-jaret.cantu@timesys.com


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