hwmon: (lm85) Use boolean to determine if VID5 is configured

ADT7463 and ADT7468 optionally support VID5 instead of the standard +12V
measurement input. Use a boolean to identify the chip configuration instead of
hardcoding it several times.

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