hwmon: (w83795) Move register reads to dedicated functions

Move initial register reads out of probe, to dedicated functions.
This makes the code clearer, and will be needed if we want to delay
calling these functions until they are needed, or want to call them
periodically.

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