R600/SI: Reorganize SIInstructions.td

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206902 91177308-0d34-0410-b5e6-96231b3b80d8
R600: Emit error instead of unreachable on function call

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206904 91177308-0d34-0410-b5e6-96231b3b80d8