eval_beamsearch_ngram.py not working
**Describe the bug**

eval_beamsearch_ngram.py not working because logprobs argument is not defined in rnnt_model.transcribe
**Steps/Code to reproduce bug**

run eval_beamsearch_ngram.py as described in  https://docs.nvidia.com/deeplearning/nemo/user-guide/docs/en/main/asr/asr_language_modeling.html#evaluate-by-beam-search-decoding-and-n-gram-lm

**Expected behavior**

If I remove logprobs argument, it produces string and makes an error because it is fed to softmax.

**Environment overview (please complete the following information)**

 - Environment location: [Bare-metal, Docker, Cloud(specify cloud provider - AWS, Azure, GCP, Collab)]
 - Method of NeMo install: [pip install or from source]. Please specify exact commands you used to install.
 - If method of install is [Docker], provide `docker pull` & `docker run` commands used

**Environment details**

If NVIDIA docker image is used you don't need to specify these.
Otherwise, please provide:
- OS version
- PyTorch version
- Python version

**Additional context**

Add any other context about the problem here.
Example: GPU model
