IB/iser: use new shared CQ mechanism

Have the driver use shared CQs provided by the rdma core driver.  Since
this provides similar functionality to iser_comp it has been removed. Now
there is no reason to allocate very large CQs when the driver is loaded
while gaining the advantage of shared CQs.

Link: https://lore.kernel.org/r/20200722135629.49467-1-maxg@mellanox.com


Signed-off-by: Yamin Friedman <yaminf@mellanox.com>
Acked-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>