Perf: arm64: Add additional CPUHP state for perf events

Previous hotplug notifier was overwriting cpu online notifiers which
are needed by various drivers in the kernel. Instead create a new state
right after CPUHP_AP_NOTIFY_ONLINE just for perf.

Change-Id: Ie740315c621a176ceff3ca13f52a48716eef5782
[rananta@codeaurora.org: resolved trivial merge conflicts]
Signed-off-by: Kyle Yan <kyan@codeaurora.org>
Signed-off-by: Raghavendra Rao Ananta <rananta@codeaurora.org>