net/mlx5: accelerate DV flow counter query

net/mlx5: accelerate DV flow counter query

All the DV counters are cashed in the PMD memory and are contained in
pools which are contained in containers according to the counters
allocation type - batch or single.

Currently, the flow counter query is done synchronously in pool
resolution means that on the user request a FW command is triggered to
read all the counters in the pool.

A new feature of devX to asynchronously read batch of flow counters
allows to accelerate the user query operation.

Using the DPDK host thread, the PMD periodically triggers asynchronous
query in pool resolution for all the counter pools and an interrupt is
triggered by the FW when the values are updated.
In the interrupt handler the pool counter values raw data is replaced
using a double buffer algorithm (very fast).
In the user query, the PMD just returns the last query values from the
PMD cache - no system-calls and FW commands are triggered from the user
control thread on query operation!

More synchronization is added with the host thread:
        Container resize uses double buffer algorithm.
        Pools growing in container uses atomic operation.
        Pool query buffer replace uses a spinlock.
        Pool minimum devX counter ID uses atomic operation.

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