net: mscc: ocelot: add action of police on vcap_is2

Ocelot has 384 policers that can be allocated to ingress ports,
QoS classes per port, and VCAP IS2 entries. ocelot_police.c
supports to set policers which can be allocated to police action
of VCAP IS2. We allocate policers from maximum pol_id, and
decrease the pol_id when add a new vcap_is2 entry which is
police action.

Signed-off-by: Xiaoliang Yang <xiaoliang.yang_1@nxp.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>