IB/uverbs: Add CQ moderation capability to query_device

The query_device function can now obtain the maximum values for
cq_max_count and cq_period, needed for CQ moderation.
cq_max_count is a 16 bits number that determines the number
of CQEs to accumulate before generating an event.
cq_period is a 16 bits number that determines the timeout in micro
seconds from the last event generated, upon which a new event will
be generated even if cq_max_count was not reached.

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>