Convert a PPC test from grep to FileCheck

Convert this test to FileCheck, and improve it to check for the instructions it
is trying to exclude instead of checking for register use (especially because
grepping for r1 can be thrown off, for example, by a use of r12).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195979 91177308-0d34-0410-b5e6-96231b3b80d8