RDMA/hns: Let software PI/CI grow naturally

The hardware can truncate PI/CI when posting or polling, the driver does
not need to do truncation. Therefore keep the software's PI/CI consistent
with it in the hardware.

Link: https://lore.kernel.org/r/1589982799-28728-2-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@mellanox.com>