[llvm] [RISCV] Add missing RISCVMaskedPseudo for TIED pseudos (PR #86787)

[Philip Reames via llvm-commits]

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

LGTM w/comment.

Note that this is a slightly larger change than it first appears.  We're not adding the annotation for *another* instance of a TIED pseudo, this is the *first* instance of the TIED pseudo.  

Looking at the existing code in performCombineVMergeAndVOps, I don't see a problem, but please make sure you audit this code closely - if you haven't already.  

https://github.com/llvm/llvm-project/pull/86787