ARM: perf: set cpu affinity to support multiple PMUs

ARM: perf: set cpu affinity to support multiple PMUs

In a system with multiple heterogeneous CPU PMUs and each PMUs can handle
events on a subset of CPUs, probably belonging a the same cluster.

This patch introduces a cpumask to track which CPUs each PMU supports.
It also updates armpmu_event_init to reject cpu-specific events being
initialised for unsupported CPUs. Since process-specific events can be
initialised for all the CPU PMUs,armpmu_start/stop/add are modified to
prevent from being added on unsupported CPUs.

Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>