Fix op test (PaddlePaddle#32231)

Author: liym27

python/paddle/fluid/tests/unittests/op_test.py

@@ -1452,7 +1452,8 @@ def check_grad_with_place(self,
         # FIXME: Replace numeric_place with place to calculate numeric_grads.
         # NOTE(liym27): There is an unknown error when call op.run() on NPUPlace, which
         # needs to be fixed.
-        if self.__class__.use_npu == True:
+        if hasattr(self.__class__,
+                   "use_npu") and self.__class__.use_npu == True:
             numeric_place = paddle.CPUPlace()
         else:
             numeric_place = place