Function _FusedBatchNormGradGrad

Returns the gradients for the 3 inputs of FusedBatchNormGrad. Args: op: The FusedBatchNormGradOp for which we need to compute gradients. *grad: An argument list for tensors of gradients wrt the outputs with grad[0] as grad_grad_x, grad[1] as grad_grad_scale, grad[2] as grad_gr

(op, *grad)