RDMA/ipoib: Distribute cq completion vector better

Currently ipoib choose cq completion vector based on port number, when HCA
only have one port, all the interface recv queue completion are bind to cq
completion vector 0.

To better distribute the load, use same method as __ib_alloc_cq_any to
choose completion vector, with the change, each interface now use
different completion vectors.

Link: https://lore.kernel.org/r/20201013074342.15867-1-jinpu.wang@cloud.ionos.com


Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Reviewed-by: Gioh Kim <gi-oh.kim@cloud.ionos.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>