AMDGPU: Remove superfluous string attributes from tests

Also fix v_mac.ll not testing right thing for fneg

llvm-svn: 275129
diff --git a/llvm/test/CodeGen/AMDGPU/ds_read2st64.ll b/llvm/test/CodeGen/AMDGPU/ds_read2st64.ll
index 725c3f9..7a8a206 100644
--- a/llvm/test/CodeGen/AMDGPU/ds_read2st64.ll
+++ b/llvm/test/CodeGen/AMDGPU/ds_read2st64.ll
@@ -258,5 +258,5 @@
 ; Function Attrs: nounwind readnone
 declare i32 @llvm.amdgcn.workitem.id.y() #1
 
-attributes #0 = { nounwind "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-realign-stack" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #0 = { nounwind }
 attributes #1 = { nounwind readnone }