RDMA/hns: Package operations of rq inline buffer into separate functions

Here packages the codes of allocating and freeing rq inline buffer in
hns_roce_create_qp_common function in order to reduce the complexity.

Link: https://lore.kernel.org/r/1567068102-56919-3-git-send-email-liweihang@hisilicon.com


Signed-off-by: Lijun Ou <oulijun@huawei.com>
Signed-off-by: Weihang Li <liweihang@hisilicon.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>