R600: Add intrinsics for mad24

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209456 91177308-0d34-0410-b5e6-96231b3b80d8
R600: Expand mad24 for GPUs without it

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209457 91177308-0d34-0410-b5e6-96231b3b80d8
R600: Expand mul24 for GPUs without it

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209458 91177308-0d34-0410-b5e6-96231b3b80d8