[bufferization] Simplify code. NFCI.

Author: d0k

mlir/lib/Dialect/Bufferization/Transforms/OneShotModuleBufferize.cpp

@@ -342,10 +342,8 @@ getFuncOpsOrderedByCalls(ModuleOp moduleOp,
         return callOp->emitError() << "expected a CallOp";
       func::FuncOp calledFunction = getCalledFunction(callOp);
       assert(calledFunction && "could not retrieved called func::FuncOp");
-      auto it = callerMap.try_emplace(calledFunction, DenseSet<Operation *>{});
-      it.first->getSecond().insert(callOp);
-      if (calledBy[calledFunction].count(funcOp) == 0) {
-        calledBy[calledFunction].insert(funcOp);
+      callerMap[calledFunction].insert(callOp);
+      if (calledBy[calledFunction].insert(funcOp).second) {
         numberCallOpsContainedInFuncOp[funcOp]++;
       }
       return WalkResult::advance();