cpuidle: Drop unnecessary type cast in cpuidle_poll_time()

The data type of the target_residency_ns field in struct cpuidle_state
is u64, so it does not need to be cast into u64.

Get rid of the unnecessary type cast.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpuidle/cpuidle.c

@@ -381,7 +381,7 @@ u64 cpuidle_poll_time(struct cpuidle_driver *drv,
 		if (dev->states_usage[i].disable)
 			continue;
 
-		limit_ns = (u64)drv->states[i].target_residency_ns;
+		limit_ns = drv->states[i].target_residency_ns;
 		break;
 	}