[x86] Do not convert to cmp32 for Atom arch by Sergey Okunev

Differential Revision: http://llvm-reviews.chandlerc.com/D2824


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205288 91177308-0d34-0410-b5e6-96231b3b80d8