arm_pmu: note IRQs and PMUs per-cpu

To support ACPI systems, we need to request IRQs before we know the
associated PMU, and thus we need some percpu variable that the IRQ
handler can find the PMU from.

As we're going to request IRQs without the PMU, we can't rely on the
arm_pmu::active_irqs mask, and similarly need to track requested IRQs
with a percpu variable.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
[will: made armpmu_count_irq_users static]
Signed-off-by: Will Deacon <will.deacon@arm.com>

include/linux/perf/arm_pmu.h

@@ -75,7 +75,6 @@ enum armpmu_attr_groups {
 
 struct arm_pmu {
 	struct pmu	pmu;
-	cpumask_t	active_irqs;
 	cpumask_t	supported_cpus;
 	char		*name;
 	irqreturn_t	(*handle_irq)(int irq_num, void *dev);