dsa: bcm_sf2: use flow_rule infrastructure

Update this driver to use the flow_rule infrastructure, hence we can use
the same code to populate hardware IR from ethtool_rx_flow and the
cls_flower interfaces.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>