thermal: extend the cooling device API to include power information

Add three optional callbacks to the cooling device interface to allow
them to express power.  In addition to the callbacks, add helpers to
identify cooling devices that implement the power cooling device API.

Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Javi Merino <javi.merino@arm.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
(cherry picked from commit 35b11d2e3a66279a477e36cefb2603806295b8ce)
Signed-off-by: Kevin Hilman <khilman@linaro.org>