hwmon: (lm85) Clean up the handling of additional resolution bits

The way the lm85 driver currently handles the additional resolution
bits some chips have for the voltage and temperature measurements is
quite complex. This is my attempt to make it simpler.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Juerg Haefliger <juergh at gmail.com>
Signed-off-by: Mark M. Hoffman <mhoffman@lightlink.com>