[AArch64] Update test case to pass with post-RA MI scheduler.

Check that the post RA scheduler is being skipped, regardless of
whether it's the top-down list latency scheduler or the post-RA
MI scheduler.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217725 91177308-0d34-0410-b5e6-96231b3b80d8