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/arm/mach-realview/core.c b/arch/arm/mach-realview/core.c
index 2f04d54..b07cb9b 100644
--- a/arch/arm/mach-realview/core.c
+++ b/arch/arm/mach-realview/core.c
@@ -511,7 +511,7 @@
 	.set_mode	= timer_set_mode,
 	.set_next_event	= timer_set_next_event,
 	.rating		= 300,
-	.cpumask	= CPU_MASK_ALL,
+	.cpumask	= cpu_all_mask,
 };
 
 static void __init realview_clockevents_init(unsigned int timer_irq)