[AMDGPU] Clarify ReqdWorkGroupSize and MaxFlatWorkGroupSize metadata

- If ReqdWorkGroupSize is present it must have all elements >=1.
- If MaxFlatWorkGroupSize must be consistent with ReqdWorkGroupSize.
- Remove FixedWorkGroupSize as now equivalent to ReqdWorkGroupSize.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@323829 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed