R600/SI: Default to no single precision denormals.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213017 91177308-0d34-0410-b5e6-96231b3b80d8
R600: Add denormal handling subtarget features.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213018 91177308-0d34-0410-b5e6-96231b3b80d8