Rename the function related to QP buffer to make the code more readable.

Link: https://lore.kernel.org/r/1589982799-28728-6-git-send-email-liweihang@huawei.comSigned-off-by: Xi Wang <wangxi11@huawei.com>
Signed-off-by: Weihang Li <liweihang@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>