drivers: thermal: Add hotplug cooling device

Add hotplug cooling device. This cooling device can be used in thermal
condition after core isolation is triggered. This will help any process
from triggering a isolated core.

Change-Id: I4e77a85d12951c839b513eb9a05462fcdf1ce6e2
Signed-off-by: Ram Chandrasekar <rkumbako@codeaurora.org>