drivers/perf: Initialise return value in armpmu_request_irqs()

If a PMU doesn't have any IRQs, we should return 0 from
armpmu_request_irqs(), rather than uninitialised stack.
Signed-off-by: Will Deacon <will.deacon@arm.com>

drivers/perf/arm_pmu_platform.c

@@ -160,7 +160,7 @@ static int pmu_parse_irqs(struct arm_pmu *pmu)
 static int armpmu_request_irqs(struct arm_pmu *armpmu)
 {
 	struct pmu_hw_events __percpu *hw_events = armpmu->hw_events;
-	int cpu, err;
+	int cpu, err = 0;
 
 	for_each_cpu(cpu, &armpmu->supported_cpus) {
 		int irq = per_cpu(hw_events->irq, cpu);