irq: make variable static

This variable is only used in the source file, so make it static.
Signed-off-by: NRoel Kluin <roel.kluin@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

kernel/irq/proc.c

@@ -220,7 +220,7 @@ void unregister_handler_proc(unsigned int irq, struct irqaction *action)
 	}
 }
 
-void register_default_affinity_proc(void)
+static void register_default_affinity_proc(void)
 {
 #ifdef CONFIG_SMP
 	proc_create("irq/default_smp_affinity", 0600, NULL,