mlxsw: spectrum_switchdev: Use ops->vxlan_join() when adding VLAN to VxLAN device

Currently mlxsw_sp_switchdev_vxlan_vlan_add() always calls
mlxsw_sp_bridge_8021q_vxlan_join() because VLANs were only ever added to
a VLAN-filtering bridge, which is only 802.1q bridge.

This set adds support for VxLAN with 802.1ad bridge, so VLAN-filtering
bridge is not only 802.1q.

Call ops->vxlan_join(), so mlxsw_sp_bridge_802{1q, 1ad}_vxlan_join()
will be called according to bridge type.

This is needed to ensure that VxLAN with 802.1ad bridge will be vetoed
in Spectrum-1 with the next patch.

Signed-off-by: Amit Cohen <amcohen@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>