hwmon: (f71882fg) Check for hwmon powerdown state

More F8000 prep work. Take over the checking if the hwmon part is not
powered down from the standalone f8000 driver.

This check is valid for all supported models.

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