thermal: devfreq_cooling: use a copy of device status

Devfreq cooling needs to now the correct status of the device in order
to operate. Devfreq framework can change the device status in the
background. To mitigate issues make a copy of the status structure and use
it for internal calculations.

In addition this patch adds normalization function, which also makes sure
that whatever data comes from the device, the load will be in range from 1
to 1024.

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/20201210143014.24685-3-lukasz.luba@arm.com