hwmon: (coretemp) Abstract core_temp helpers

coretemp driver has an obscure and fragile logic for handling package
and core temperature data.

Place the logic in newly introduced helpers for further optimizations.

No functional change.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Link: https://lore.kernel.org/r/20240202092144.71180-9-rui.zhang@intel.com


Signed-off-by: Guenter Roeck <linux@roeck-us.net>