hwmon: (pc87427) Add support for the second logical device

The second logical device contains the voltage and temperature
registers. We have to extend the driver to support a second logical
device before we can add support for these features.

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