net/sched: cls_flower: Support matching on SCTP ports

Support matching on SCTP ports in the same way that matching
on TCP and UDP ports is already supported.

Example usage:

tc qdisc add dev eth0 ingress

tc filter add dev eth0 protocol ip parent ffff: \
        flower indev eth0 ip_proto sctp dst_port 80 \
        action drop

Signed-off-by: Simon Horman <simon.horman@netronome.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>