sctp: xmit sctp packet always return no route error

Commit 'net: skb->dst accessors'(adf30907)
broken the sctp protocol stack, the sctp packet can never be sent out after
Eric Dumazet's patch, which have typo in the sctp code.
Signed-off-by: NWei Yongjun <yjwei@cn.fujitsu.com>
Acked-by: NEric Dumazet <eric.dumazet@gmail.com>
Acked-by: NVlad Yasevich <vladisalv.yasevich@hp.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/sctp/output.c

@@ -407,7 +407,7 @@ int sctp_packet_transmit(struct sctp_packet *packet)
 	}
 	dst = dst_clone(tp->dst);
 	skb_dst_set(nskb, dst);
-	if (dst)
+	if (!dst)
 		goto no_route;
 
 	/* Build the SCTP header.  */