Bluetooth: Add L2CAP channel to skb private data

Adding the channel to the skb private data makes possible to us know which
channel the skb we have came from.

Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

include/net/bluetooth/bluetooth.h

@@ -282,6 +282,7 @@ struct bt_skb_cb {
 	__u8 incoming;
 	__u16 expect;
 	__u8 force_active;
+	struct l2cap_chan *chan;
 	struct l2cap_ctrl control;
 	struct hci_req_ctrl req;
 	bdaddr_t bdaddr;

net/bluetooth/l2cap_sock.c

@@ -1174,6 +1174,8 @@ static struct sk_buff *l2cap_sock_alloc_skb_cb(struct l2cap_chan *chan,
 	if (!skb)
 		return ERR_PTR(err);
 
+	bt_cb(skb)->chan = chan;
+
 	return skb;
 }