[X86][SSE] Reuse zeroable element mask in lowerVectorShuffleAsZeroOrAnyExtend. NFCI

Don't regenerate a zeroable element mask with computeZeroableShuffleElements when its already available.

llvm-svn: 286044
GitOrigin-RevId: 725174694ae7140747ea7acaa6afcae3dbf985f0
1 file changed