[X86] getFauxShuffleMask - only handle VTRUNC nodes with matching src/dst sizes#134161

RKSimon merged 2 commits intollvm:mainllvm/llvm-project:mainfrom

RKSimon:x86-faux-shuffle-vtruncRKSimon/llvm-project:x86-faux-shuffle-vtruncCopy head branch name to clipboard