sctp: fix return value check in __sctp_rcv_asconf_lookup

As Ben Hutchings noticed, this check should have been inverted: the call
returns true in case of success.
Reported-by: Ben Hutchings <ben@decadent.org.uk>
Fixes: 0c5dc070 ("sctp: validate from_addr_param return")
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Reviewed-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sctp/input.c

@@ -1203,7 +1203,7 @@ static struct sctp_association *__sctp_rcv_asconf_lookup(
 	if (unlikely(!af))
 		return NULL;
 
-	if (af->from_addr_param(&paddr, param, peer_port, 0))
+	if (!af->from_addr_param(&paddr, param, peer_port, 0))
 		return NULL;
 
 	return __sctp_lookup_association(net, laddr, &paddr, transportp);