cpuidle: fix cpuidle time and usage overflow

cpuidle C-state sysfs node time and usage are very easy to overflow because
they are all of unsigned int type, time will overflow within about two hours,
usage will take longer time to overflow, but they are increasing for ever.

This patch will convert them to unsigned long long.

Signed-off-by: Yi Yang <yi.y.yang@intel.com>
Acked-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index d73663a..d42deb3 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -67,7 +67,7 @@
 	/* enter the state and update stats */
 	dev->last_residency = target_state->enter(dev, target_state);
 	dev->last_state = target_state;
-	target_state->time += dev->last_residency;
+	target_state->time += (unsigned long long)dev->last_residency;
 	target_state->usage++;
 
 	/* give the governor an opportunity to reflect on the outcome */