RDMA/hns: Add atomic support

This patch adds atomic operations for hip08, includes fetchadd and cmpswap
operation.  In order to enable atomic, the driver needs to do the
following steps:

1. Enable the atomic caps for RoCE device
2. Post the wqe context of atomic type
3. Configure the atomic type of mtpt

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