RDMA/hns: Set access flags of hip08 RoCE

This patch refactors the code of setting access flags
for RDMA operation as well as adds the scene when
attr->max_dest_rd_atomic is zero.

Signed-off-by: Lijun Ou <oulijun@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>