Fix LayoutLMv2 test
# What does this PR do?

This PR fixes a failing LayoutLMv2 test, `test_torch_encode_plus_sent_to_model`.

It also removes `requires_scatter`, because LayoutLMv2 doesn't depend on it.
The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_15939). All of your documentation changes will be reflected on that endpoint.