[AMDGPU] Produce madak and madmk from the two-address pass

These two instructions are normally selected, but when the
two address pass converts mac into mad we end up with the
mad where we could have one of these.

Differential Revision: https://reviews.llvm.org/D37389

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@312928 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed