selftests: forwarding: vxlan_bridge_1d_port_8472: New test

This simple wrapper reruns the VXLAN ping test with a port number of
8472.

Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>