[llvm] [RISCV] Don't fold vmerge.vvm or vmv.v.v into vredsum.vs if AVL changed (PR #99006)

[Philip Reames via llvm-commits]

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

LGTM

(Yuck, this is a nasty bug.)

https://github.com/llvm/llvm-project/pull/99006