net/mlx5: workaround drop action with old kernel

net/mlx5: workaround drop action with old kernel

Currently, there are two types of drop action implementation
in the PMD. One is the DR (Direct Rules) dummy placeholder drop
action and another is the dedicated dummy queue drop action.
When creates flow on the root table with DR drop action, the
action will be converted to MLX5_IB_ATTR_CREATE_FLOW_FLAGS_DROP
Verbs attribute in rdma-core.

In some inbox systems, MLX5_IB_ATTR_CREATE_FLOW_FLAGS_DROP Verbs
attribute may not be supported in the kernel driver. Create flow
with drop action on the root table will be failed as it is not
supported. In this case, the dummy queue drop action should be
used instead of DR dummy placeholder drop action.

This commit adds the DR drop action support detect on the root
table. If MLX5_IB_ATTR_CREATE_FLOW_FLAGS_DROP Verbs is not
supported in the system, a dummy queue will be used as drop
action.

Fixes: da845ae9d7c1 ("net/mlx5: fix drop action for Direct Rules/Verbs")
Cc: stable@dpdk.org
Signed-off-by: Suanming Mou <suanmingm@nvidia.com>
Acked-by: Matan Azrad <matan@nvidia.com>