nit: needed sanity checks for fsdp2

[kmehant]

What does this PR do?

Simle nit fixes needed for using fsdp2 in a pre-configured environment.

This has been discussed in #3394

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
• Did you read the contributor guideline,
  Pull Request section?
• Was this discussed/approved via a Github issue or the forum? Please add a link
  to it if that's the case. Initial FSDP2 support #3394
• Did you make sure to update the documentation with your changes? Here are the
  documentation guidelines, and
  here are tips on formatting docstrings.
• Did you write any new necessary tests?

Who can review?

Anyone in the community is free to review the PR once the tests have passed. Feel free to tag
members/contributors who may be interested in your PR.

@SunMarc or @zach-huggingface or @S1ro1

[SunMarc]

Thanks !