tipc: fix compatibility bug

In commit d999297c3dbbe7fdd832f7fa4ec84301e170b3e6
("tipc: reduce locking scope during packet reception") we introduced
a new function tipc_link_proto_rcv(). This function contains a bug,
so that it sometimes by error sends out a non-zero link priority value
in created protocol messages.

The bug may lead to an extra link reset at initial link establising
with older nodes. This will never happen more than once, whereafter
the link will work as intended.

We fix this bug in this commit.

Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/tipc/link.c

@@ -1639,7 +1639,7 @@ static int tipc_link_proto_rcv(struct tipc_link *l, struct sk_buff *skb,
 			rcvgap = peers_snd_nxt - l->rcv_nxt;
 		if (rcvgap || (msg_probe(hdr)))
 			tipc_link_build_proto_msg(l, STATE_MSG, 0, rcvgap,
-						  0, l->mtu, xmitq);
+						  0, 0, xmitq);
 		tipc_link_release_pkts(l, msg_ack(hdr));
 
 		/* If NACK, retransmit will now start at right position */