update comment

experimental/torch_xla2/torch_xla2/ops/jaten.py

@@ -1955,10 +1955,10 @@ def _aten_native_batch_norm(input, weight, bias, running_mean, running_var, trai
 
   Args:
       input: Input data (N, C, ...)
+      weight: Scaling factor (gamma) (C,), can be None
+      bias: Shift factor (beta) (C,), can be None
       running_mean: Running mean of input (C,)
       running_var: Running variance of input (C,)
-      weight: Optional scaling factor (gamma) (C,)
-      bias: Optional shift factor (beta) (C,)
       training: Whether to perform training-time or inference-time batch norm
       momentum: Momentum factor for updating running mean and variance
       eps: Small constant added to the variance to avoid division by zero