net: mscc: ocelot: drop port argument from qos_policer_conf_set

The "port" argument is used for nothing else except printing on the
error path. Print errors on behalf of the policer index, which is less
confusing anyway.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>