AMDGPU: R600 code splitting cleanup

Move a few functions only used by R600 to R600 specific code,
fix header macros to stop using R600, mark classes as final.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@263204 91177308-0d34-0410-b5e6-96231b3b80d8
32 files changed