[AArch64] Fix op mask detection in performZExtDeinterleaveShuffleCombine#126054

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

davemgreen:gh-a64-fixdeinterleavebottomdavemgreen/llvm-project:gh-a64-fixdeinterleavebottomCopy head branch name to clipboard