RDMA/hns: Set desc_dma_addr for zero when free cmq desc

In order to avoid illegal use for desc_dma_addr of ring,
it needs to set it zero when free cmq desc.
Signed-off-by: Lijun Ou <oulijun@huawei.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/hns/hns_roce_hw_v2.c

@@ -617,6 +617,8 @@ static void hns_roce_free_cmq_desc(struct hns_roce_dev *hr_dev,
 	dma_unmap_single(hr_dev->dev, ring->desc_dma_addr,
 			 ring->desc_num * sizeof(struct hns_roce_cmq_desc),
 			 DMA_BIDIRECTIONAL);
+
+	ring->desc_dma_addr = 0;
 	kfree(ring->desc);
 }