hwmon: (applesmc) Dynamic creation of temperature files

The current driver creates temperature files based on a list
of temperature keys given per device. Apart from slow adaption
to new machine models, the number of sensors also depends on
the number of processors. This patch looks up the temperature
keys dynamically, thereby supporting all models.
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>