net: sparx5: mdb add/del handle non-sparx5 devices

When adding/deleting mdb entries on other net_devices, eg., tap
interfaces, it should not crash.

Fixes: 3bacfcc ("net: sparx5: Add mdb handlers")
Signed-off-by: Casper Andersson <casper.casan@gmail.com>
Reviewed-by: Steen Hegelund <Steen.Hegelund@microchip.com>
Link: https://lore.kernel.org/r/20220630122226.316812-1-casper.casan@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: cappe987

drivers/net/ethernet/microchip/sparx5/sparx5_switchdev.c

@@ -396,6 +396,9 @@ static int sparx5_handle_port_mdb_add(struct net_device *dev,
 	u32 mact_entry;
 	int res, err;
 
+	if (!sparx5_netdevice_check(dev))
+		return -EOPNOTSUPP;
+
 	if (netif_is_bridge_master(v->obj.orig_dev)) {
 		sparx5_mact_learn(spx5, PGID_CPU, v->addr, v->vid);
 		return 0;
@@ -466,6 +469,9 @@ static int sparx5_handle_port_mdb_del(struct net_device *dev,
 	u32 mact_entry, res, pgid_entry[3];
 	int err;
 
+	if (!sparx5_netdevice_check(dev))
+		return -EOPNOTSUPP;
+
 	if (netif_is_bridge_master(v->obj.orig_dev)) {
 		sparx5_mact_forget(spx5, v->addr, v->vid);
 		return 0;