!212 Fix an issue of inversion_attack

From: @jxlang910
Reviewed-by: @liu_luobin,@zhidanliu,@pkuliuliu
Signed-off-by: @pkuliuliu

mindarmour/privacy/evaluation/inversion_attack.py

@@ -65,7 +65,7 @@ class InversionLoss(Cell):
             Tensor, inversion attack loss of the current iteration.
         """
         output = self._network(input_data)
-        loss_1 = self._mse_loss(output, target_features) / self._mse_loss(target_features, 0)
+        loss_1 = self._mse_loss(output, target_features) / self._mse_loss(target_features, self._zeros(target_features))
 
         data_shape = self._get_shape(input_data)
         if self._device_target == 'CPU':
@@ -85,7 +85,7 @@ class InversionLoss(Cell):
             data_copy_2[:, :, :, :(data_shape[2] - 1)] = input_data[:, :, :, 1:]
             loss_2 = self._mse_loss(input_data, data_copy_1) + self._mse_loss(input_data, data_copy_2)
 
-        loss_3 = self._mse_loss(input_data, 0)
+        loss_3 = self._mse_loss(input_data, self._zeros(input_data))
 
         loss = loss_1*self._weights[0] + loss_2*self._weights[1] + loss_3*self._weights[2]
         return loss