thermal: int340x: processor_thermal: Platform temperature control documentation

Update documentation of attributes for platform temperature control.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Link: https://patch.msgid.link/20250429000110.236243-4-srinivas.pandruvada@linux.intel.com


Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>