net: ethernet: ti: am65-cpsw: enable bc/mc storm prevention support

net: ethernet: ti: am65-cpsw: enable bc/mc storm prevention support

This patch enables support for ingress broadcast(BC)/multicast(MC) packets
rate limiting in TI AM65x CPSW driver (the corresponding ALE support was
added in previous patch) by implementing HW offload for simple tc-flower
with policer action with matches on dst_mac/mask:
 - ff:ff:ff:ff:ff:ff/ff:ff:ff:ff:ff:ff has to be used for BC packets rate
limiting (exact match)
 - 01:00:00:00:00:00/01:00:00:00:00:00 fixed value has to be used for MC
packets rate limiting

The CPSW supports MC/BC packets rate limiting in packets/sec and affects
all ingress MC/BC packets and serves as BC/MC storm prevention feature.

Examples:
- BC rate limit to 1000pps:
  tc qdisc add dev eth0 clsact
  tc filter add dev eth0 ingress flower skip_sw dst_mac ff:ff:ff:ff:ff:ff \
  action police pkts_rate 1000 pkts_burst 1 drop

- MC rate limit to 20000pps:
  tc qdisc add dev eth0 clsact
  tc filter add dev eth0 ingress flower skip_sw dst_mac 01:00:00:00:00:00/01:00:00:00:00:00 \
  action police rate pkts_rate 20000 pkts_burst 1 drop

  pkts_burst - not used.

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>