arm64: topology: Handle AMU FIE setup on CPU hotplug

arm64: topology: Handle AMU FIE setup on CPU hotplug

Currently, when a cpufreq policy is created, the AMU FIE setup process
checks all CPUs in the policy -- including those that are offline. If any
of these CPUs are offline at that time, their AMU capability flag hasn't
been verified yet, leading the check fail. As a result, AMU FIE is not
enabled, even if the CPUs that are online do support it.

Later, when the previously offline CPUs come online and report AMU support,
there's no mechanism in place to re-enable AMU FIE for the policy. This
leaves the entire frequency domain without AMU FIE, despite being eligible.

Restrict the initial AMU FIE check to only those CPUs that are online at
the time the policy is created, and allow CPUs that come online later to
join the policy with AMU FIE enabled.

Signed-off-by: Lifeng Zheng <zhenglifeng1@huawei.com>
Acked-by: Beata Michalska <beata.michalska@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>