cpumask: convert struct clock_event_device to cpumask pointers.

Impact: change calling convention of existing clock_event APIs

struct clock_event_timer's cpumask field gets changed to take pointer,
as does the ->broadcast function.

Another single-patch change.  For safety, we BUG_ON() in
clockevents_register_device() if it's not set.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/mips/sni/time.c b/arch/mips/sni/time.c
index 796e3ce..69f5f88 100644
--- a/arch/mips/sni/time.c
+++ b/arch/mips/sni/time.c
@@ -80,7 +80,7 @@
 	struct irqaction *action = &a20r_irqaction;
 	unsigned int cpu = smp_processor_id();
 
-	cd->cpumask             = cpumask_of_cpu(cpu);
+	cd->cpumask             = cpumask_of(cpu);
 	clockevents_register_device(cd);
 	action->dev_id = cd;
 	setup_irq(SNI_A20R_IRQ_TIMER, &a20r_irqaction);