QQuickWebEngineView: silence deprecation warning

Silence deprecation warning "'QJSValue::QJSValue': Use fromUtf8, QStringLiteral, or QLatin1StringView" when build with
-DFEATURE_webengine_printing_and_pdf=OFF

Change-Id: I2f165329caf6fc8bab4ec78c828c5d4a3cb923e7
Reviewed-by: Peter Varga <pvarga@inf.u-szeged.hu>

src/webenginequick/api/qquickwebengineview.cpp

@@ -1681,7 +1681,7 @@ void QQuickWebEngineView::printToPdf(const QJSValue &callback, PrintedPageSizeId
 
     // Call back with null result.
     QJSValueList args;
-    args.append(QJSValue(QByteArray().data()));
+    args.append(QJSValue(QLatin1String("")));
     QJSValue callbackCopy = callback;
     callbackCopy.call(args);
 #endif