Unused "embedding_size" in bert attention
Author: amar-jay
Pull request: yes

The embedding_size is not used.

# What does this PR do?

Fixes unused code in bert attention
Fixes a minor typo in code


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Comments:
Hi @amar-jay, thanks for opening this PR! 

To resolve the quality checks here, you'll need to run `make fix-copies`. The difficulty here is that, even though embedding size isn't part of the bert config - this attention class is copied in many cases throughout the library and might be protecting some hidden behaviour. 

The check was added in #3257 but I'm not sure why. In the spirit of chesterton's fence let's ask @LysandreJik who added it. 

This issue has been automatically marked as stale because it has not had recent activity. If you think this still needs to be addressed please comment on this thread.

Please note that issues that do not follow the [contributing guidelines](https://github.com/huggingface/transformers/blob/main/CONTRIBUTING.md) are likely to be ignored.