mt76: mt7663u: fix potential memory leak in mcu message handler

Fix potential memory leak in mcu message handler on error condition.

Fixes: eb99cc95 ("mt76: mt7615: introduce mt7663u support")
Acked-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt7615/usb_mcu.c

@@ -34,7 +34,6 @@ mt7663u_mcu_send_message(struct mt76_dev *mdev, struct sk_buff *skb,
 
 	ret = mt76u_bulk_msg(&dev->mt76, skb->data, skb->len, NULL,
 			     1000, ep);
-	dev_kfree_skb(skb);
 	if (ret < 0)
 		goto out;
 
@@ -43,6 +42,7 @@ mt7663u_mcu_send_message(struct mt76_dev *mdev, struct sk_buff *skb,
 
 out:
 	mutex_unlock(&mdev->mcu.mutex);
+	dev_kfree_skb(skb);
 
 	return ret;
 }