cpuidle: Clean up cpuidle_enable_device() error handling a bit

Do not fetch per CPU drv if cpuidle_curr_governor is NULL
to avoid useless per CPU processing.
Signed-off-by: Gaurav Jindal <gauravjindal1104@gmail.com>
[ rjw: Subject & changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpuidle/cpuidle.c

@@ -388,9 +388,12 @@ int cpuidle_enable_device(struct cpuidle_device *dev)
 	if (dev->enabled)
 		return 0;
 
+	if (!cpuidle_curr_governor)
+		return -EIO;
+
 	drv = cpuidle_get_cpu_driver(dev);
 
-	if (!drv || !cpuidle_curr_governor)
+	if (!drv)
 		return -EIO;
 
 	if (!dev->registered)