Bluetooth: use kfree_skb() instead of kfree()

sk_buffs should be freed using kfree_skb().
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>

net/bluetooth/l2cap_core.c

@@ -4284,7 +4284,7 @@ static inline int l2cap_data_channel(struct l2cap_conn *conn, u16 cid, struct sk
 	if (!chan) {
 		BT_DBG("unknown cid 0x%4.4x", cid);
 		/* Drop packet and return */
-		kfree(skb);
+		kfree_skb(skb);
 		return 0;
 	}