hwmon: (coretemp) Add support for dynamic ttarget

Tjmax value retrieved from MSR_IA32_TEMPERATURE_TARGET can be changed at
runtime when the Intel SST-PP (Intel Speed Select Technology -
Performance Profile) level is changed. As a result, the ttarget value
also becomes dyamic.

Improve the code to always get updated ttarget value.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Link: https://lore.kernel.org/r/20221113153145.32696-4-rui.zhang@intel.com


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