Add helper function to get data module for llava
<!-- pylint-output-strict-mode-true -->

beep boop 🤖: 🚨 The following files must be fixed before merge!

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Your code was analyzed with PyLint. The following annotations have been identified:

```
************* Module nemo.collections.vlm.api
nemo/collections/vlm/api.py:1:0: C0116: Missing function or method docstring (missing-function-docstring)

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Your code has been rated at 9.74/10
```

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Mitigation guide:

* Add sensible and useful docstrings to functions and methods
* For trivial methods like getter/setters, consider adding `# pylint: disable=C0116` inside the function itself
* To disable multiple functions/methods at once, put a `# pylint: disable=C0116` before the first and a `# pylint: enable=C0116` after the last.

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Thank you for improving NeMo's documentation! This PR is stale because it has been open for 14 days with no activity. Remove stale label or comment or update or this will be closed in 7 days. This PR was closed because it has been inactive for 7 days since being marked as stale.
Just extracts data module definition to a helper function.