When get_hw_stats is called, query and return the optional counter
statistic as well.

Link: https://lore.kernel.org/r/20211008122439.166063-14-markzhang@nvidia.comSigned-off-by: NAharon Landau <aharonl@nvidia.com>
Signed-off-by: NLeon Romanovsky <leonro@nvidia.com>
Signed-off-by: NMark Zhang <markzhang@nvidia.com>
Signed-off-by: NJason Gunthorpe <jgg@nvidia.com>