RDMA/hns: Stop doorbell update while qp state error

There are two paths to update qp producer index into hardware now, one
path is doorbell in post verbs (send and recv), the another is mailbox in
modify qp verb which is called by flush process. This will lead the
hardware to be broken to correctly generate flush cqe.  With stopping
doorbell update and holding qp spinlock in modify qp during flush process,
the problem can be solved.

Fixes: 0425e3e6 ("RDMA/hns: Support flush cqe for hip08 in kernel space")
Link: https://lore.kernel.org/r/1582367158-27030-3-git-send-email-liuyixian@huawei.com


Signed-off-by: Yixian Liu <liuyixian@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>