arch_topology,arm64: make counter-based frequency invariance generic

Move the arm64 functionality for counter and cpufreq-based frequency
invariance from the arm64 topology code to the generic arch_topology
driver.

This enables the unification of the two sources for frequency invariance
for all users of the arch_topology driver while allowing the use of
counters other than the arm64 Activity Monitors (AMUs).

Signed-off-by: Ionela Voinescu <ionela.voinescu@arm.com>