code: private long numPointWiseParams(SeparableConvolution2D layerConf) {
          val nIn = layerConf.getNIn();
          val nOut = layerConf.getNOut();
          val depthMultiplier = layerConf.getDepthMultiplier();
  
          return (nIn * depthMultiplier) * nOut;
      }
docs: For the point-wise convolution part we have (nIn * depthMultiplier) many
  input maps and nOut output maps. Kernel size is (1, 1) for this operation.
  
  @param layerConf layer configuration of the separable conv2d layer
  @return number of parameters of the point-wise convolution operation