hwmon: Don't export thermistor beta

Deprecate the use of thermistor beta values as thermal sensor types.
No driver supports changing the beta value anyway.

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>