Revert "[AMDGPU] Cope with SelectionDAG::UpdateNodeOperands returning a different SDNode (#65340)"

This reverts commit 11171d8.

Broke ASAN bot.

Author: fmayer

llvm/lib/Target/AMDGPU/SIISelLowering.cpp

@@ -13133,9 +13133,7 @@ SDNode *SITargetLowering::adjustWritemask(MachineSDNode *&Node,
         continue;
     } else {
       SDValue Op = DAG.getTargetConstant(Idx, SDLoc(User), MVT::i32);
-      SDNode *NewUser = DAG.UpdateNodeOperands(User, SDValue(NewNode, 0), Op);
-      if (NewUser != User)
-        DAG.ReplaceAllUsesWith(SDValue(User, 0), SDValue(NewUser, 0));
+      DAG.UpdateNodeOperands(User, SDValue(NewNode, 0), Op);
     }
 
     switch (Idx) {