drivers: thermal: pe_sensor: Add Policy Engine sensor

Add Policy Engine(PE) sensor recommendation as a sensor with thermal
framework. PE will recommend a mitigation level based on the operating
level of CX/MX clients. Registering this recommendations as sensor enables
the user to provide thermal zone configuration to mitigate cooling devices
for different policy engine recommendations.

Change-Id: I65e1a8baad62957482daca493987d6cd51eee3ef
Signed-off-by: Ram Chandrasekar <rkumbako@codeaurora.org>