selftests: vxlan_bridge: Test flood with unresolved FDB entry

selftests: vxlan_bridge: Test flood with unresolved FDB entry

Extend flood test to configure FDB entry with unresolved destination IP,
check that packets are not sent twice.

Without the previous patch which handles such scenario in mlxsw, the
tests fail:

$ TESTS='test_flood' ./vxlan_bridge_1d.sh
Running tests with UDP port 4789
TEST: VXLAN: flood                                                  [ OK ]
TEST: VXLAN: flood, unresolved FDB entry                            [FAIL]
        vx2 ns2: Expected to capture 10 packets, got 20.

$ TESTS='test_flood' ./vxlan_bridge_1q.sh
INFO: Running tests with UDP port 4789
TEST: VXLAN: flood vlan 10                                          [ OK ]
TEST: VXLAN: flood vlan 20                                          [ OK ]
TEST: VXLAN: flood vlan 10, unresolved FDB entry                    [FAIL]
        vx10 ns2: Expected to capture 10 packets, got 20.
TEST: VXLAN: flood vlan 20, unresolved FDB entry                    [FAIL]
        vx20 ns2: Expected to capture 10 packets, got 20.

With the previous patch, the tests pass.

Signed-off-by: Amit Cohen <amcohen@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/7bc96e317531f3bf06319fb2ea447bd8666f29fa.1742224300.git.petrm@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>