Fix FP-Quant quantization fallback CPU dispatch.
Author: BlackSamorez
Pull request: yes

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Added a workaround for a hard-coded missing key CPU dispatch that broke pre-quantized model loading for FP-Quant.
`weight` was assumed to be missing and auto-dispatched to CPU but it's a parameter that gets set to `None` in post-loading (in `pre_forward`).

Fixed FP-Quant test typos.

Blocked by #41613 too.


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Models:

- text models: @ArthurZucker @Cyrilvallez
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Comments:
**[For maintainers]** Suggested jobs to run (before merge)

run-slow: fp_quant_integration

@SunMarc may you take a look, please?

The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_41619). All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.