PM / devfreq: Add missing error code in devfreq_add_device()

Set err code in the error path before jumping to the end of the function.

Fixes: 4dc3bab8 ("PM / devfreq: Add support delayed timer for polling mode")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>

drivers/devfreq/devfreq.c

@@ -823,6 +823,7 @@ struct devfreq *devfreq_add_device(struct device *dev,
 	if (devfreq->profile->timer < 0
 		|| devfreq->profile->timer >= DEVFREQ_TIMER_NUM) {
 		mutex_unlock(&devfreq->lock);
+		err = -EINVAL;
 		goto err_dev;
 	}