The work of B. Tang was supported partly by Hunan Provincial Innovation Foundation for Postgraduate (No. CX2016B249) and Hunan Provincial Natural Science Foundation of China (No. 2018JJ3019). The work of N. Dong was supported partly by the Hunan Provincial Natural Science Foundation of China (Nos. 14JJ2114, 2017JJ2071) and the Excellent Youth Foundation and General Foundation of Hunan Educational Department (Nos. 17B071, 17C0466).