mlxsw: spectrum: Avoid possible NULL pointer dereference

In case we got an FDB notification for a port that doesn't exist we
execute an FDB entry delete to prevent it from re-appearing the next
time we poll for notifications.

If the operation failed we would trigger a NULL pointer dereference as
'mlxsw_sp_port' is NULL.

Fix it by reporting the error using the underlying bus device instead.

Fixes: 12f1501e7511 ("mlxsw: spectrum: remove FDB entry in case we get unknown object notification")
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/spectrum_switchdev.c

@@ -1497,8 +1497,7 @@ do_fdb_op:
 	err = mlxsw_sp_port_fdb_uc_op(mlxsw_sp, local_port, mac, fid,
 				      adding, true);
 	if (err) {
-		if (net_ratelimit())
-			netdev_err(mlxsw_sp_port->dev, "Failed to set FDB entry\n");
+		dev_err_ratelimited(mlxsw_sp->bus_info->dev, "Failed to set FDB entry\n");
 		return;
 	}
 
@@ -1558,8 +1557,7 @@ do_fdb_op:
 	err = mlxsw_sp_port_fdb_uc_lag_op(mlxsw_sp, lag_id, mac, fid, lag_vid,
 					  adding, true);
 	if (err) {
-		if (net_ratelimit())
-			netdev_err(mlxsw_sp_port->dev, "Failed to set FDB entry\n");
+		dev_err_ratelimited(mlxsw_sp->bus_info->dev, "Failed to set FDB entry\n");
 		return;
 	}