metag: Use irq_set_affinity instead of homebrewn code

There is no point in having an incomplete copy of irq_set_affinity()
for the hotplug irq migration code.

Use the core function instead and while at it switch to
for_each_active_irq()
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: metag <linux-metag@vger.kernel.org>
Signed-off-by: James Hogan <james.hogan@imgtec.com>

arch/metag/kernel/irq.c

@@ -261,18 +261,6 @@ int __init arch_probe_nr_irqs(void)
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
-static void route_irq(struct irq_data *data, unsigned int irq, unsigned int cpu)
-{
-	struct irq_desc *desc = irq_to_desc(irq);
-	struct irq_chip *chip = irq_data_get_irq_chip(data);
-	unsigned long flags;
-
-	raw_spin_lock_irqsave(&desc->lock, flags);
-	if (chip->irq_set_affinity)
-		chip->irq_set_affinity(data, cpumask_of(cpu), false);
-	raw_spin_unlock_irqrestore(&desc->lock, flags);
-}
-
 /*
  * The CPU has been marked offline.  Migrate IRQs off this CPU.  If
  * the affinity settings do not allow other CPUs, force them onto any
@@ -281,10 +269,9 @@ static void route_irq(struct irq_data *data, unsigned int irq, unsigned int cpu)
 void migrate_irqs(void)
 {
 	unsigned int i, cpu = smp_processor_id();
-	struct irq_desc *desc;
 
-	for_each_irq_desc(i, desc) {
-		struct irq_data *data = irq_desc_get_irq_data(desc);
+	for_each_active_irq(i) {
+		struct irq_data *data = irq_get_irq_data(i);
 		unsigned int newcpu;
 
 		if (irqd_is_per_cpu(data))
@@ -300,11 +287,8 @@ void migrate_irqs(void)
 					    i, cpu);
 
 			cpumask_setall(data->affinity);
-			newcpu = cpumask_any_and(data->affinity,
-						 cpu_online_mask);
 		}
-
-		route_irq(data, i, newcpu);
+		irq_set_affinity(i, data->affinity);
 	}
 }
 #endif /* CONFIG_HOTPLUG_CPU */