R600: Remove unused include

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214728 91177308-0d34-0410-b5e6-96231b3b80d8
Use the known address space constant rather than checking it

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214729 91177308-0d34-0410-b5e6-96231b3b80d8