RDMA/hns: Add method to query WQE buffer's address

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



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

If a uQP works in DCA mode, the userspace driver need to get the buffer's
address in DCA memory pool by calling the 'HNS_IB_METHOD_DCA_MEM_QUERY'
method after the QP was attached by calling the
'HNS_IB_METHOD_DCA_MEM_ATTACH' method.

This method will return the DCA mem object's key and the offset to let the
userspace driver get the WQE's virtual address in DCA memory pool.

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>