Fixes "Clocksource tsc unstable (delta = -974982308 ns)" problem.

[ IDE was unlucky to be initialized at the same time that
  clocksource watchdog triggers and was blamed for the issue. ]

Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Cc: Lars Winterfeld <lars.winterfeld@tu-ilmenau.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
---
 kernel/time/tick-sched.c |    2 ++
 1 file changed, 2 insertions(+)

Index: b/kernel/time/tick-sched.c
===================================================================
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -21,6 +21,7 @@
 #include <linux/sched.h>
 #include <linux/tick.h>
 #include <linux/module.h>
+#include <linux/clocksource.h>
 
 #include <asm/irq_regs.h>
 
@@ -153,6 +154,7 @@ void tick_nohz_update_jiffies(void)
 	local_irq_restore(flags);
 
 	touch_softlockup_watchdog();
+	clocksource_touch_watchdog();
 }
 
 static void tick_nohz_stop_idle(int cpu)