flow_dissector: add tipc support

The flows are hashed on the sending node address, which allows us
to spread out the TIPC link processing to RPS enabled cores. There
is no point to include the destination address in the hash as that
will always be the same for all inbound links. We have experimented
with a 3-tuple hash over [srcnode, sport, dport], but this showed to
give slightly lower performance because of increased lock contention
when the same link was handled by multiple cores.

Signed-off-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Erik Hugne <erik.hugne@ericsson.com>
Reviewed-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>