watchdog: f71808e_wdt: Add F81865 support

Adds watchdog enable support for Fintek F81865 Super-IO chip to
Fintek wdt driver (f71808e_wdt)

Tested and verified on Lanner LEC-3030 Industrial PC

Datasheet references:
http://www.hardwaresecrets.com/datasheets/F81865_V028P.pdf
http://www.alldatasheet.com/datasheet-pdf/pdf/406317/FINTEK/F81865.html



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