nvme-rdma: use new shared CQ mechanism

Has the driver use shared CQs providing ~10%-20% improvement as seen in
the patch introducing shared CQs. Instead of opening a CQ for each QP
per controller connected, a CQ for each QP will be provided by the RDMA
core driver that will be shared between the QPs on that core reducing
interrupt overhead.

Signed-off-by: Yamin Friedman <yaminf@mellanox.com>
Signed-off-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Or Gerlitz <ogerlitz@mellanox.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>