cpumask: remove last assignment to mask field of struct irqaction.

This snuck in after the patch which removed all the others.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/time.c b/arch/x86/kernel/time.c
index e293ac5..dcb00d2 100644
--- a/arch/x86/kernel/time.c
+++ b/arch/x86/kernel/time.c
@@ -93,7 +93,6 @@
 
 void __init setup_default_timer_irq(void)
 {
-	irq0.mask = cpumask_of_cpu(0);
 	setup_irq(0, &irq0);
 }