vdpa/mlx5: Fix wrong mac address deletion

Delete the old MAC from the table and not the new one which is not there
yet.

Fixes: baf2ad3f ("vdpa/mlx5: Add RX MAC VLAN filter support")
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Eli Cohen <elic@nvidia.com>
Message-Id: <20221114131759.57883-4-elic@nvidia.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>