Fix typo in call to irq_to_desc()

Fix typo in call to irq_to_desc()
Signed-off-by: NMorten H. Larsen <m-larsen@post6.tele.dk>
Signed-off-by: NMatt Turner <mattst88@gmail.com>

arch/alpha/kernel/irq.c

@@ -44,7 +44,7 @@ static char irq_user_affinity[NR_IRQS];
 
 int irq_select_affinity(unsigned int irq)
 {
-	struct irq_desc *desc = irq_to_desc[irq];
+	struct irq_desc *desc = irq_to_desc(irq);
 	static int last_cpu;
 	int cpu = last_cpu + 1;