arm64: Provide an AMU-based version of arch_freq_get_on_cpu

With the Frequency Invariance Engine (FIE) being already wired up with
sched tick and making use of relevant (core counter and constant
counter) AMU counters, getting the average frequency for a given CPU,
can be achieved by utilizing the frequency scale factor which reflects
an average CPU frequency for the last tick period length.

The solution is partially based on APERF/MPERF implementation of
arch_freq_get_on_cpu.

Suggested-by: Ionela Voinescu <ionela.voinescu@arm.com>
Signed-off-by: Beata Michalska <beata.michalska@arm.com>
Reviewed-by: Prasanna Kumar T S M <ptsm@linux.microsoft.com>
Reviewed-by: Sumit Gupta <sumitg@nvidia.com>
Link: https://lore.kernel.org/r/20250131162439.3843071-4-beata.michalska@arm.com


Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>