[SCTP]: Set ports in every address returned by sctp_getladdrs()

Thomas Dreibholz has reported that port numbers are not filled
in the results of sctp_getladdrs() when the socket was bound
to an ephemeral port.  This is only true, if the address was
not specified either.  So, fill in the port number correctly.

Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>