RDMA/hns: Fix accessing invalid dip_ctx during destroying QP

If it fails to modify QP to RTR, dip_ctx will not be attached. And
during detroying QP, the invalid dip_ctx pointer will be accessed.

Fixes: faa6244 ("RDMA/hns: Fix different dgids mapping to the same dip_idx")
Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>
Signed-off-by: Junxian Huang <huangjunxian6@hisilicon.com>
Link: https://patch.msgid.link/20241220055249.146943-3-huangjunxian6@hisilicon.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>

drivers/infiniband/hw/hns/hns_roce_hw_v2.c

@@ -5619,6 +5619,9 @@ static void put_dip_ctx_idx(struct hns_roce_dev *hr_dev,
 {
 	struct hns_roce_dip *hr_dip = hr_qp->dip;
 
+	if (!hr_dip)
+		return;
+
 	xa_lock(&hr_dev->qp_table.dip_xa);
 
 	hr_dip->qp_cnt--;