hwmon/f71882fg: Make number of temps configurable

Make the temp sysattr array for the standard models a 2d array, which allows
to use it for models with less temperatures too. This is a preparation
patch for adding support for more different models.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>