RDMA/hns: Fix to support 64K page for srq

SRQ's page size configuration of BA and buffer should depend on current
PAGE_SHIFT, or it can't work in scenario of 64K page.

Fixes: c7bcb134

 ("RDMA/hns: Add SRQ support for hip08 kernel mode")
Link: https://lore.kernel.org/r/1571908917-16220-2-git-send-email-liweihang@hisilicon.com
Signed-off-by: Lijun Ou <oulijun@huawei.com>
Signed-off-by: Weihang Li <liweihang@hisilicon.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>