hwmon: (f71882fg) Add support for the F71858F

Add support for the hwmon part of the Fintek F71858FG superio IC to the
f71882fg driver. Many thanks to Jelle de Jong for lending me a motherboard 
with this superio on it.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>