RDMA/hns: Bugfix for querying qkey

The qkey queried through the query ud qp verb is a fixed value and it
should be read from qp context.

Fixes: 926a01dc ("RDMA/hns: Add QP operations support for hip08 SoC")
Link: https://lore.kernel.org/r/1588931159-56875-2-git-send-email-liweihang@huawei.com


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