RDMA/hns: Rename CMDQ head/tail pointer to PI/CI

mainline inclusion
from mainline-v5.12-rc1
commit 4511624a
category: bugfix
bugzilla: 174002
CVE:NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=4511624a3514e5eb4af7aa4d7fb0b491dd06ae5a

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The same name represents opposite meanings in new/old driver, it is hard
to maintain, so rename them to PI/CI.

Link: https://lore.kernel.org/r/1621482876-35780-2-git-send-email-liweihang@huawei.com


Signed-off-by: Lang Cheng <chenglang@huawei.com>
Signed-off-by: Weihang Li <liweihang@huawei.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: wangsirong <wangsirong@huawei.com>
Reviewed-by: ChunZhi Hu <huchunzhi@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>