Thermal: Intel SoC: DTS thermal IOSF core

This is becoming a common feature for Intel SoCs to expose the additional
digital temperature sensors (DTSs) using side band interface (IOSF). This
change remove common IOSF DTS handler function from the existing driver
intel_soc_dts_thermal.c and creates a stand alone module, which can
be selected from the SoC specific drivers. In this way there is less
code duplication.

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