libhns: Fix UD 0 msg length err using new post send

When msg length is 0, the sge num should also be 0, otherwise there
will be a cqe error.

Fixes: 36446a56eea5 ("libhns: Extended QP supports the new post send mechanism")
Signed-off-by: Junxian Huang <huangjunxian6@hisilicon.com>

providers/hns/hns_roce_u_hw_v2.c

diff --git a/providers/hns/hns_roce_u_hw_v2.c b/providers/hns/hns_roce_u_hw_v2.c
index 79da7f5..9f34fb4 100644
--- a/providers/hns/hns_roce_u_hw_v2.c
+++ b/providers/hns/hns_roce_u_hw_v2.c
@@ -2517,10 +2517,13 @@
 		return;
 
 	wqe->msg_len = htole32(length);
-	hr_reg_write(wqe, UDWQE_SGE_NUM, 1);
+	hr_reg_write(wqe, UDWQE_SGE_NUM, !!length);
 	sge_idx = qp->sge_info.start_idx & (qp->ex_sge.sge_cnt - 1);
 	hr_reg_write(wqe, UDWQE_MSG_START_SGE_IDX, sge_idx);
 
+	if (!length)
+		goto out;
+
 	dseg = get_send_sge_ex(qp, sge_idx);
 
 	dseg->lkey = htole32(lkey);
@@ -2529,6 +2532,7 @@
 
 	qp->sge_info.start_idx++;
 
+out:
 	rdma_tracepoint(rdma_core_hns, post_send,
 			ibv_qp->qp_base.context->device->name, ibv_qp->wr_id,
 			1, ibv_qp->qp_base.qp_num,