IB/mlx5: Add CQ moderation capability to query_device

query_device can now obtain the maximum values for
cq_max_count and cq_period, needed for cq moderation.

Signed-off-by: Yonatan Cohen <yonatanc@mellanox.com>
Reviewed-by: Majd Dibbiny <majd@mellanox.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>