AMDGPU: Remove unnecessary and on conditional branch

The comment explaining why this was necessary is incorrect
in its description of v_cmp's behavior for inactive workitems.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@286134 91177308-0d34-0410-b5e6-96231b3b80d8
10 files changed