thermal: intel_pch_thermal: Fix enable check on Broadwell-DE

Using the TSDSS flag to determine whether the thermal sensor is
enabled is problematic. Broadwell-DE (Xeon D-1500) does not support
dynamic shutdown and the TSDSS flag always reads 0 (contrary to the
current datasheet). Even on hardware supporting dynamic shutdown, the
driver does nothing to configure it, and the dynamic shutdown state
should not prevent the driver from loading. The ETS flag itself
indicates whether the thermal sensor is enabled, so use it instead of
the TSDSS flag on all hardware platforms.

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