RDMA/hns: Add a check for current state before modifying QP

RDMA/hns: Add a check for current state before modifying QP

BugLink: https://bugs.launchpad.net/bugs/1902115
[ Upstream commit e0ef0f68c4c0d85b1eb63f38d5d10324361280e8 ]

It should be considered an illegal operation if the ULP attempts to modify
a QP from another state to the current hardware state. Otherwise, the ULP
can modify some fields of QPC at any time. For example, for a QP in state
of RTS, modify it from RTR to RTS can change the PSN, which is always not
as expected.

Fixes: 9a4435375cd1 ("IB/hns: Add driver files for hns RoCE driver")
Link: https://lore.kernel.org/r/1598353674-24270-1-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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Ian May <ian.may@canonical.com>