watchdog: f71808e_wdt: Add F81966 support

This adds watchdog support the Fintek F81966 Super I/O chip.
Testing was done on the Aaeon SSE-OPTI

Signed-off-by: AaeonIot <sophiehu@aaeon.com.tw>
Signed-off-by: Chia-Lin Kao (AceLan) <acelan.kao@canonical.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20211117024052.2427539-1-acelan.kao@canonical.com


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