RDMA/hns: Fix the bug with updating rq head pointer when flush cqe

[ Upstream commit 9c6ccc03 ]

When flush cqe with srq, the driver disable to update the rq head pointer
into the hardware.

Signed-off-by: Lijun Ou <oulijun@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>