[clang] [Clang][AMDGPU] Add ``amdgcn_av("none")`` attribute for atomic expressions (PR #199622)

[Sameer Sahasrabuddhe via cfe-commits]

================
@@ -2017,6 +2018,9 @@ Value *CodeGenFunction::EmitAMDGPUBuiltinExpr(unsigned BuiltinID,
         Builder.CreateAtomicRMW(BinOp, Ptr, Val, AO, SSID);
     if (Volatile)
       RMW->setVolatile(true);
+    if (!AMDGCNAVMode.empty()) {
----------------
ssahasra wrote:

Fixed this and the rest.

https://github.com/llvm/llvm-project/pull/199622