Limit 'media:' prefix check based on files touched in the patch

If a patch does not touch media drivers or includes, then make the 'media:' check optional.

It's a bit tricky, but I would probably try something like this:

If all touched files in a patch are media drivers, media includes, media bindings or media documentation, then 'media:' is required. If it is a mix between media and non-media files, then it is optional (i.e. a warning only), if it doesn't touch on those at all, then don't do the check.