selftests: mlxsw: devlink_trap_tunnel_ipip: Align topology drawing correctly

As part of adding same test for GRE tunnel with IPv6 underlay, wrong
alignments were found, fix them.

Signed-off-by: Amit Cohen <amcohen@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>