mlxsw: spectrum_trap: Adjust default policer burst size for Spectrum-{2, 3}

On the Spectrum-{2,3} ASICs the minimum burst size of the packet trap
policers needs to be 40% of the configured rate. Otherwise, intermittent
drops are observed even when the incoming packet rate is slightly lower
than the configured policer rate.

Adjust the burst size of the registered packet trap policers so that
they do not violate above mentioned limitation.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>