This is the 1st part of consolidating how the max compute capacity is
used in the scheduler and how we calculate the frequency for a level of
utilization.
Fix some unconsistancy when computing frequency for an utilization. There
can be a mismatch between energy model and schedutil.
Next step will be to make a difference between the original
max compute capacity of a CPU and what is currently available when
there is a capping applying forever (i.e. seconds or more).