arm_pmu: Use of_cpu_node_to_id helper

Use the new generic helper, of_cpu_node_to_id(), to map a
a phandle to the logical CPU number while parsing the
PMU irq affinity.

Cc: Will Deacon <[e-mail]>
Acked-by: Mark Rutland <[e-mail]>
Signed-off-by: Suzuki K Poulose <[e-mail]>
Signed-off-by: Will Deacon <[e-mail]>

drivers/perf/arm_pmu_platform.c

···
 		return -EINVAL;
 	}
 
-	/* Now look up the logical CPU number */
-	for_each_possible_cpu(cpu) {
-		struct device_node *cpu_dn;
-
-		cpu_dn = of_cpu_device_node_get(cpu);
-		of_node_put(cpu_dn);
-
-		if (dn == cpu_dn)
-			break;
-	}
-
-	if (cpu >= nr_cpu_ids) {
+	cpu = of_cpu_node_to_id(dn);
+	if (cpu < 0) {
 		pr_warn("failed to find logical CPU for %s\n", dn->name);
+		cpu = nr_cpu_ids;
 	}
 
 	of_node_put(dn);