Make tensor device correct when ACCELERATE_TORCH_DEVICE is defined

[kiszk]

What does this PR do?

Fixes #31750

This PR fixes the issue of returning an incorrect device (cpu) of tensors passed to a model with accelerate when ACCELERATE_TORCH_DEVICE is defined as privateuseone:0. When known accelerators are not available, a function should check whether ACCELERATE_TORCH_DEVICE is defined or not before returning cpu.

It looks hard to write a test problem with privateuseone:0. I manually tested the issue was fixed with this PR. Any idea to add tests are appreciated.

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Who can review?

@muellerzr @SunMarc

[amyeroberts]

Thanks for fixing this!

Just want to double check with @muellerzr before merge this is correct

[muellerzr]

Thanks, this makes sense to me as we do similar in Accelerate in the end :)

[HuggingFaceDocBuilderDev]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

[LysandreJik]

Thanks @kiszk!