Simplify code and reduce code size by using the new hwmon
registration API.
Other changes:
- Convert to use regmap, and drop local caching. This avoids reading
registers unnecessarily, and uses regmap for caching of non-volatile
registers.
- Add support for temp2_max, temp2_max_alarm, temp2_max_hyst, and
temp2_offset.
- Order include files alphabetically
- Drop FSF address
- Check errors from register read and write functions and report
to userspace.
- Accept negative hysteresis values. While unlikely, a maximum limit
_can_ be set to a value smaller than 31 degrees C, which makes negative
hysteresis values possible.