sched/uclamp: Make asym_fits_capacity() use util_fits_cpu()

Use the new util_fits_cpu() to ensure migration margin and capacity
pressure are taken into account correctly when uclamp is being used
otherwise we will fail to consider CPUs as fitting in scenarios where
they should.

s/asym_fits_capacity/asym_fits_cpu/ to better reflect what it does now.

Fixes: b4c9c9f1 ("sched/fair: Prefer prev cpu in asymmetric wakeup path")
Signed-off-by: Qais Yousef <qais.yousef@arm.com>