thermal: int340x: Introduce processor reporting device

The Int340x thermal provides a processor thermal device, which
is used to control processor thermal states. These devices are
either reported as a PCI device or an ACPI device. This
device provides power limits, control states and optional
temperature.
This change implements minimal requirements to expose processor
power limits which can be used during thermal power limiting.
Power limits are exposed via an attribute group called
"power_limits" under the device. The exported attributes
are:
power_limit_0_max_uw
power_limit_1_max_uw
power_limit_0_min_uw
power_limit_1_min_uw
power_limit_0_tmin_us
power_limit_1_tmin_us
power_limit_0_tmax_us
power_limit_1_tmax_us
power_limit_0_step_uw
power_limit_1_step_uw

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>