R600: Remove dead code

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210994 91177308-0d34-0410-b5e6-96231b3b80d8
R600: Report that integer division is expensive.

Divides by weird constants now emit much better code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210995 91177308-0d34-0410-b5e6-96231b3b80d8