Implements the flow counters read wrapper.
Reviewed-by: NYishai Hadas <yishaih@mellanox.com>
Signed-off-by: NRaed Salem <raeds@mellanox.com>
Signed-off-by: NLeon Romanovsky <leonro@mellanox.com>
Signed-off-by: NJason Gunthorpe <jgg@mellanox.com>