SCTP: Pick the correct port when binding to 0.

sctp_bindx() allows the use of unspecified port.  The problem is
that every address we bind to ends up selecting a new port if
the user specified port 0.  This patch allows re-use of the
already selected port when the port from bindx was 0.
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>

net/sctp/socket.c

@@ -353,6 +353,7 @@ SCTP_STATIC int sctp_do_bind(struct sock *sk, union sctp_addr *addr, int len)
 	 * The function sctp_get_port_local() does duplicate address
 	 * detection.
 	 */
+	addr->v4.sin_port = htons(snum);
 	if ((ret = sctp_get_port_local(sk, addr))) {
 		if (ret == (long) sk) {
 			/* This endpoint has a conflicting address. */