dip_idx and dgid should be a one-to-one mapping relationship, but when
qp_num loops back to the start number, it may happen that two different
dgid are assiociated to the same dip_idx incorrectly.

One solution is to store the qp_num that is not assigned to dip_idx in an
array. When a dip_idx needs to be allocated to a new dgid, an spare qp_num
is extracted and assigned to dip_idx.

Fixes: f91696f2 ("RDMA/hns: Support congestion control type selection according to the FW")
Link: https://lore.kernel.org/r/1629884592-23424-4-git-send-email-liangwenpeng@huawei.comSigned-off-by: Junxian Huang <huangjunxian4@hisilicon.com>
Signed-off-by: Yangyang Li <liyangyang20@huawei.com>
Signed-off-by: Wenpeng Liang <liangwenpeng@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>