hwmon: (pmbus) Introduce infrastructure to detect sensors and limit registers

This commit replaces hard-coded sensor and limit register detection code
with table based sensor detection. This change eliminates code block repetition
and reduces code size.
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Reviewed-by: Tom Grennan <tom.grennan@ericsson.com>