[llvm] LoopVectorize: update comment following 63d8058 (NFC) (PR #91120)

[Florian Hahn via llvm-commits]

https://github.com/fhahn approved this pull request.

LGTM, thanks! As suggested elsewhere I'd recommend to use the more compact [LV] tag in the title instead of the more verbose `LoopVectorize:` (you will ned to update the title of the PR or adjust when merging the change)

https://github.com/llvm/llvm-project/pull/91120