The flow counter has been introduced in early versions of the driver to
aid in debugging. It is no longer needed and can harm performance.

Remove it.
Signed-off-by: Eli Cohen <elic@nvidia.com>
Message-Id: <20220411122942.225717-2-elic@nvidia.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>