Variables `hidden_steps` (line 306) and `_SUPPORTED_ARCH` (line 337) in `transformer_bottleneck.py` are not defined
**Describe the bug**

Variables `hidden_steps` (line 306) and `_SUPPORTED_ARCH` (line 337) in https://github.com/NVIDIA/NeMo/blob/main/nemo/collections/nlp/modules/common/transformer/transformer_bottleneck.py are not defined.
