RDMA/hns: Reorganize hns_roce_create_cq()

Encapsulate two subprocesses into functions.

Link: https://lore.kernel.org/r/1616815294-13434-3-git-send-email-liweihang@huawei.com


Signed-off-by: Yixing Liu <liuyixing1@huawei.com>
Signed-off-by: Weihang Li <liweihang@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>