Maemo: Fix device config model's data() member function.

This subtle bug would lead to weird behavior of QComboBox on Windows.

Reviewed-by: kh1

src/plugins/qt4projectmanager/qt-maemo/maemodeviceconfiglistmodel.cpp

@@ -125,7 +125,7 @@ QVariant MaemoDeviceConfigListModel::data(const QModelIndex &index, int role) co
 {
     if (!index.isValid() || index.row() >= rowCount()
         || role != Qt::DisplayRole)
-        return QString();
+        return QVariant();
     return MaemoDeviceConfigurations::instance().devConfigs().at(index.row()).name;
 }