hwmon: (w83627ehf) Properly report thermal diode sensors

The w83627ehf driver is improperly reporting thermal diode sensors as
type 2, instead of 3. This caused "sensors" and possibly other
monitoring tools to report these sensors as "transistor" instead of
"thermal diode".

Furthermore, diode subtype selection (CPU vs. external) is only
supported by the original W83627EHF/EHG. All later models only support
CPU diode type, and some (NCT6776F) don't even have the register in
question so we should avoid reading from it.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: stable@kernel.org
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>