drivers/thermal/cpufreq_cooling: Use private callback ops for each cooling device

drivers/thermal/cpufreq_cooling: Use private callback ops for each cooling device

It is very unlikely that one CPU cluster would have the EM and some other
won't have it (because EM registration failed or DT lacks needed entry).
Although, we should avoid modifying global variable with callbacks anyway.
Redesign this and add safety for such situation.

Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lore.kernel.org/r/20220613124327.30766-2-lukasz.luba@arm.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>