thermal: devfreq_cooling: add new registration functions with Energy Model

The Energy Model (EM) framework supports devices such as Devfreq. Create
new registration function which automatically register EM for the thermal
devfreq_cooling devices. This patch prepares the code for coming changes
which are going to replace old power model with the new EM.

Reviewed-by: Ionela Voinescu <ionela.voinescu@arm.com>
Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20201210143014.24685-4-lukasz.luba@arm.com