selftests: forwarding: vxlan_bridge_1d: Reconfigure & rerun tests

The ordering of the topology creation can have impact on whether a
driver is successful in offloading VXLAN. Therefore add a pseudo-test
that reshuffles bits of the topology, and then reruns the same suite of
tests again to make sure that the new setup is supported as well.

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>