[Kunlun]add multi xpu support for PaddleClas about dygraph (#690)

* add multi xpu support for PaddleClas about dygraph

* add dygraph multi xpu support

tools/train.py

@@ -56,7 +56,16 @@ def main(args):
     config = get_config(args.config, overrides=args.override, show=True)
     # assign the place
     use_gpu = config.get("use_gpu", True)
-    place = paddle.set_device('gpu' if use_gpu else 'cpu')
+    use_xpu = config.get("use_xpu", False)
+    assert (
+        use_gpu and use_xpu
+    ) is not True, "gpu and xpu can not be true in the same time in static mode!"
+    if use_gpu:
+        place = paddle.set_device('gpu')
+    elif use_xpu:
+        place = paddle.set_device('xpu')
+    else:
+        place = paddle.set_device('cpu')
 
     trainer_num = paddle.distributed.get_world_size()
     use_data_parallel = trainer_num != 1