hwmon: (max6650) Add support for alarms

Export the alarm flags provided by the MAX6650/MAX6651 fan-speed regulator
and monitor chips via sysfs.

Signed-off-by: Christian Engelmayer <christian.engelmayer@frequentis.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>