net/mlx5: fix redundant flow after RSS expansion

net/mlx5: fix redundant flow after RSS expansion

When RSS expand, if there is no expansion happened but completion
happened because user only input next protocol field instead of item
i.e, ether type == 0x8100 instead of VLAN, an extra flow is created with
missing item in order to filter traffic strictly.

However, after [1] and [2] the rte_flow_item_eth itself is enough to
filter out VLAN traffic, the VLAN item is not needed.

[1]: commit 09315fc83861 ("ethdev: add VLAN attributes to ethernet and VLAN items")
[2]: commit 86b59a1af671 ("net/mlx5: support VLAN matching fields")

This redundant flow will cause failure in some scenarios on group 0 due
to they are the same FTE.

Fixes: fc2dd8dd492f ("ethdev: fix expand RSS flows")
Cc: stable@dpdk.org
Signed-off-by: Xiaoyu Min <jackmin@nvidia.com>
Acked-by: Matan Azrad <matan@nvidia.com>