net: sparx5: add support for matchall mirror stats

Add support for tc matchall mirror stats. When a new matchall mirror
rule is added, the baseline stats for that port is saved.

Signed-off-by: Daniel Machon <daniel.machon@microchip.com>
Reviewed-by: Steen Hegelund <Steen.Hegelund@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>