[FIX] EVA meta device check bug + add multi-gpu functionality

[sirluk]

This PR contains

• an important bugfix for a faulty device check in eva.py.
• torch all_gather operations for all SVD Hooks to be able to leverage a higher batch size for EVA in multi-gpu setups.
• An example in the docs for using EVA with multiple GPUs

[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.

[BenjaminBossan]

Thanks a lot for these improvemens to EVA. I tried the multi-GPU script and it worked.