selftests: mlxsw: rtnetlink: Drop obsolete tests

Support for enslaving ports to LAGs with uppers will be added in the
following patches. Selftests to make sure it actually does the right thing
are ready and will be sent as a follow-up.

Similarly, ordering of MACVLAN creation and RIF creation will be relaxed
and it will be permitted to create a MACVLAN first.

Thus these two tests are obsolete. Drop them.

Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Danielle Ratson <danieller@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>