net: bt: Disconnect in case of errors sending a packet

Packets shall never fail to be sent now that they are queued, so if an
error occured there is no point in keep the channel connected.

Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

subsys/net/l2/bluetooth/bluetooth.c

@@ -114,6 +114,8 @@ static int net_bt_send(struct net_if *iface, struct net_pkt *pkt)
 
 	ret = bt_l2cap_chan_send(&conn->ipsp_chan.chan, buffer);
 	if (ret < 0) {
+		NET_ERR("Unable to send packet: %d", ret);
+		bt_l2cap_chan_disconnect(&conn->ipsp_chan.chan);
 		return ret;
 	}