[VideoMAE] Fix docstring
# What does this PR do?

This PR fixes a docstring for VideoMAE (the model doesn't have a CLS token).

Fixes #21016 
_The documentation is not available anymore as the PR was closed or merged._<|||||>Cc @ydshieh seems like the CI has only run 7 checks. Any idea why?<|||||>Because it doesn't touch any code. Tests are only run for code changes.<|||||>Because it doesn't touch any code. Tests are only run for code changes.