hwmon: (lm77) Add individual alarm files

The new libsensors needs this. As the old library never had support for
the lm77 driver, I even dropped the legacy "alarms" file.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Hans de Goede <j.w.r.degoede@hhs.nl>
Signed-off-by: Mark M. Hoffman <mhoffman@lightlink.com>