Revert "SelectionDAG: Teach the legalizer to split SETCC if VSELECT needs splitting too."

Now Hexagon and SystemZ are not happy with it :-(

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193677 91177308-0d34-0410-b5e6-96231b3b80d8