AMDGPU/GFX10: V_CMPX_xxx instructions still have an omod operand

Summary: Change-Id: If6ee98e4a723b643bc37254fc6ef8b3812db16da

Reviewers: rampitec

Subscribers: arsenm, kzhuravl, jvesely, wdng, yaxunl, dstuttard, tpr, t-tye, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62720

Change-Id: Id547ef152b2f92b24dc1c0efbf7e4467c4fb4b6e
llvm-svn: 362390