PM / devfreq: Fix leak in devfreq_dev_release()

srcu_init_notifier_head() allocates resources that need to be released
with a srcu_cleanup_notifier_head() call.

Reported by kmemleak.

Fixes: 0fe3a66 ("PM / devfreq: Add new DEVFREQ_TRANSITION_NOTIFIER notifier")
Cc: <stable@vger.kernel.org>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Dhruva Gole <d-gole@ti.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>

Author: bbrezillon

drivers/devfreq/devfreq.c

@@ -764,6 +764,7 @@ static void devfreq_dev_release(struct device *dev)
 		dev_pm_opp_put_opp_table(devfreq->opp_table);
 
 	mutex_destroy(&devfreq->lock);
+	srcu_cleanup_notifier_head(&devfreq->transition_notifier_list);
 	kfree(devfreq);
 }