net/mlx5: allow basic counter management fallback

net/mlx5: allow basic counter management fallback

In case the asynchronous devx commands are not supported in RDMA core
fallback to use a basic counter management.

Here, the PMD counters cashe is redundant and the host thread doesn't
update it. hence, each counter operation will go to the FW and the
acceleration reduces.

Signed-off-by: Matan Azrad <matan@mellanox.com>
Acked-by: Shahaf Shuler <shahafs@mellanox.com>