Rename the PAGE_ADDR_SHIFT as HNS_HW_PAGE_SHIFT to make code more
readable.

Link: https://lore.kernel.org/r/1588931159-56875-9-git-send-email-liweihang@huawei.comSigned-off-by: NXi Wang <wangxi11@huawei.com>
Signed-off-by: NWeihang Li <liweihang@huawei.com>
Signed-off-by: NJason Gunthorpe <jgg@mellanox.com>