[llvm] [LV] Fix MVE regression from #132190 (PR #141736)

[Florian Hahn via llvm-commits]

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

LGTM, thanks! Missed the earlier update. Left a few small suggestions to clean up the new test case a bit more.

https://github.com/llvm/llvm-project/pull/141736