RDMA/hns: Refactor reset state checking flow

The 'HNS_ROCE_OPC_QUERY_MB_ST' command will response the mailbox complete
status and hardware busy flag, and the complete status is only valid when
the busy flag is 0, so it's better to query these two fields at a time
rather than separately.

Link: https://lore.kernel.org/r/1616815294-13434-4-git-send-email-liweihang@huawei.com


Signed-off-by: Xi Wang <wangxi11@huawei.com>
Signed-off-by: Weihang Li <liweihang@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>