fix bug for op:NonZero

x2paddle/op_mapper/onnx_op_mapper.py

@@ -1103,7 +1103,7 @@ class ONNXOpMapper(OpMapper):
         val_x = self.graph.get_input_node(node, idx=0, copy=True)
         where_name = node.layer_name + '_where'
         node.fluid_code.add_layer("where",
-                                  inputs=val_x.layer_name + '==1',
+                                  inputs=val_x.layer_name + '!=0',
                                   output=where_name)
         dims = len(val_x.out_shapes[0])
         elements_count_val_x = reduce(lambda x, y: x * y, val_x.out_shapes[0])