PPC: Mark vector CC action for SETO and SETONE as Expand

Another bug found by llvm-stress! This fixes hitting
  llvm_unreachable("Invalid integer vector compare condition");
at the end of getVCmpInst in PPCISelDAGToDAG.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185855 91177308-0d34-0410-b5e6-96231b3b80d8