sched/cpufreq: Take cpufreq feedback into account

Aggregate the different pressures applied on the capacity of CPUs and
create a new function that returns the actual capacity of the CPU:
get_actual_cpu_capacity().

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Lukasz Luba <lukasz.luba@arm.com>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Reviewed-by: Qais Yousef <qyousef@layalina.io>
Link: https://lore.kernel.org/r/20240326091616.3696851-3-vincent.guittot@linaro.org