hwmon: (it87) Don't arbitrarily enable temperature channels

Temperature channels can be used in 2 different modes (thermistor and
thermal diode) and we don't know which one, if any, is correct for
every given board. So don't arbitrarily choose one. Instead, leave the
temperature channels untouched. They can be configured from user-space
if needed anyway.

Signed-off-by: Jean Delvare <khali@linux-fr.org>