selftests: forwarding: tc_flower: Relax success criterion

selftests: forwarding: tc_flower: Relax success criterion

The test checks that filters that match on source or destination MAC
were only hit once. A host can send more than one packet with a given
source or destination MAC, resulting in failures.

Fix by relaxing the success criterion and instead check that the filters
were not hit zero times. Using tc_check_at_least_x_packets() is also an
option, but it is not available in older kernels.

Fixes: 07e5c75184a1 ("selftests: forwarding: Introduce tc flower matching tests")
Reported-by: Mirsad Todorovac <mirsad.todorovac@alu.unizg.hr>
Closes: https://lore.kernel.org/netdev/adc5e40d-d040-a65e-eb26-edf47dac5b02@alu.unizg.hr/
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Tested-by: Mirsad Todorovac <mirsad.todorovac@alu.unizg.hr>
Reviewed-by: Hangbin Liu <liuhangbin@gmail.com>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://lore.kernel.org/r/20230808141503.4060661-13-idosch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>