RDMA/hns: Remove unused member and variable of CMDQ

RDMA/hns: Remove unused member and variable of CMDQ

last_status of structure hns_roce_v2_cmq has never been used, and the
variable named 'complete' in __hns_roce_cmq_send() is meaningless.

Fixes: a04ff739f2a9 ("RDMA/hns: Add command queue support for hip08 RoCE driver")
Link: https://lore.kernel.org/r/1612688143-28226-2-git-send-email-liweihang@huawei.com
Signed-off-by: Lang Cheng <chenglang@huawei.com>
Signed-off-by: Weihang Li <liweihang@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>