[NFC][X86] Baseline tests for AMD BdVer2 (Piledriver) Scheduler model

Adding the baseline tests in a preparatory NFC commit,
so that the actual commit shows the *diff*.

Yes, i'm aware that a few of these codegen-based sched tests
are testing wrong instructions, i will fix that afterwards.

For https://reviews.llvm.org/D52779

llvm-svn: 345462