RDMA/hns: Configure DCA mode for the userspace QP

driver inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I63KVU



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If the userspace driver assign a NULL to the field of 'buf_addr' in
'struct hns_roce_ib_create_qp' when creating QP, this means the kernel
driver need setup the QP as DCA mode. So add a QP capability bit in
response to indicate the userspace driver that the DCA mode has been
enabled.

Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>
Reviewed-by: Yangyang Li <liyangyang20@huawei.com>
Reviewed-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>