[X86][SSE] Update extractelement test in preparation for D52140

SimplifyDemandedVectorEltsForTargetNode will remove most of this test unless get rid of the undefs - still testing for align 1 which was the point of the test

Removed out of date comment as well

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@342531 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed