[TIPC]: Allow ports to receive multicast messages through native API.

This fix prevents a kernel panic if an application mistakenly sends a
multicast message to  TIPC's topology service or configuration service.

Signed-off-by: Allan Stephens <allan.stephens@windriver.com>
Signed-off-by: Per Liden <per.liden@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>