thermal: regulator_cooling: Add AOP based regulator cooling device

QTI chipsets need to place a voltage floor restriction at low
temperature as per the device operating spec. In order to place the
floor voltage restriction for regulators, AOP has to be notified with
when the low temperature reaches.

The new regulator cooling device will use the QMP messaging interface to
place a voltage floor restriction.

Change-Id: I0a3b878b356bab55ee1bb6458ea5c4016996a194
Signed-off-by: Ram Chandrasekar <rkumbako@codeaurora.org>