RDMA/hns: Refactor the hns_roce_buf allocation flow

mainline inclusion
from mainline-v5.11-rc1
commit 6f6e2dcb
category: bugfix
bugzilla: 174002
CVE:NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=6f6e2dcbb82b9b2ea304fe32635789fedd4e9868

----------------------------------------------------------------------

Add a group of flags to control the 'struct hns_roce_buf' allocation
flow, this is used to support the caller running in atomic context.

Link: https://lore.kernel.org/r/1605347916-15964-1-git-send-email-liweihang@huawei.com


Signed-off-by: Xi Wang <wangxi11@huawei.com>
Signed-off-by: Weihang Li <liweihang@huawei.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>