selftests/thermel/intel: Add test to read workload hint

Some SoCs have in built firmware support to classify current running
workload and pass to OS for making power management decisions.

This test program waits for notification of workload type change
and prints. This program can be used to test this feature and also
allows other user space programs to use as a reference.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>