net: mscc: ocelot: Implement port policers via tc command

Hardware offload of matchall classifier and police action are now
supported via the tc command.
Supported police parameters are: rate and burst.

Example:

Add:
tc qdisc add dev eth3 handle ffff: ingress
tc filter add dev eth3 parent ffff: prio 1 handle 2	\
	matchall skip_sw				\
	action police rate 100Mbit burst 10000

Show:
tc -s -d qdisc show dev eth3
tc -s -d filter show dev eth3 ingress

Delete:
tc filter del dev eth3 parent ffff: prio 1
tc qdisc del dev eth3 handle ffff: ingress

Signed-off-by: Joergen Andreasen <joergen.andreasen@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>