drivers: thermal: regulator: Add Regulator cooling device

Add a snapshot of regulator cooling device from kernel 4.9
as of 'commit <375365b94b6> ("drivers: thermal: regulator_cdev: Add a
voltage regulator cooling device")'.

Change-Id: I0c0aacf246c752ba51de6315fbde63277f3fd56c
Signed-off-by: Ram Chandrasekar <rkumbako@codeaurora.org>