clocksource.c: use init_timer_deferrable for clocksource_watchdog

clocksource_watchdog can use a deferrable timer - reduces wakeups from
idle per second.

Signed-off-by: Parag Warudkar <parag.warudkar@gmail.com>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

kernel/time/clocksource.c

@@ -175,7 +175,7 @@ static void clocksource_check_watchdog(struct clocksource *cs)
 			if (watchdog)
 				del_timer(&watchdog_timer);
 			watchdog = cs;
-			init_timer(&watchdog_timer);
+			init_timer_deferrable(&watchdog_timer);
 			watchdog_timer.function = clocksource_watchdog;
 
 			/* Reset watchdog cycles */