R600: Use the GPU type to determine the correct DataLayout v2

v2:
  - Add R600_DOUBLE_OPS for RV670
  - s/CPU/GPU/

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176440 91177308-0d34-0410-b5e6-96231b3b80d8