R600/SI: Fix hardcoded values for modifiers.

Move enums to SIDefines.h

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218610 91177308-0d34-0410-b5e6-96231b3b80d8
Fix include order

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218611 91177308-0d34-0410-b5e6-96231b3b80d8
Fixing missing C++ mode comment

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218612 91177308-0d34-0410-b5e6-96231b3b80d8