Patch GPTNeoX to use adequate FA2 if position_ids is provided

[taha-yassine]

What does this PR do?

#31629 introduced the ability to use position_ids in FlashAttention-2, but not all models were updated to support it. This PR is a straightforward extension to GPT-NeoX models.

I was looking into including GPT-2 too, but from a quick glance at the code it seems a little bit trickier.

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
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• Did you write any new necessary tests?

Who can review?

@ArthurZucker

[ArthurZucker]

Thanks for updating! 🤗