sctp: add SCTP_ADDR_MADE_PRIM event

sctp_ulpevent_nofity_peer_addr_change() would be called in
sctp_assoc_set_primary() to send SCTP_ADDR_MADE_PRIM event
when this transport is set to the primary path of the asoc.

This event is described in rfc6458#section-6.1.2:

  SCTP_ADDR_MADE_PRIM:  This address has now been made the primary
     destination address.  This notification is provided whenever an
     address is made primary.
Signed-off-by: NXin Long <lucien.xin@gmail.com>
Acked-by: NNeil Horman <nhorman@tuxdriver.com>
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>

net/sctp/associola.c

@@ -429,6 +429,8 @@ void sctp_assoc_set_primary(struct sctp_association *asoc,
 		changeover = 1 ;
 
 	asoc->peer.primary_path = transport;
+	sctp_ulpevent_nofity_peer_addr_change(transport,
+					      SCTP_ADDR_MADE_PRIM, 0);
 
 	/* Set a default msg_name for events. */
 	memcpy(&asoc->peer.primary_addr, &transport->ipaddr,