Remove default parameter in derived function

When derived function have different default value than base, it might cause
unnecessary confusion, see: https://stackoverflow.com/q/3533589

src/gui/transferlistmodel.h

@@ -86,7 +86,7 @@ public:
     int rowCount(const QModelIndex& index = QModelIndex()) const override;
     int columnCount(const QModelIndex &parent=QModelIndex()) const override;
     QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
-    bool setData(const QModelIndex &index, const QVariant &value, int role = Qt::DisplayRole) override;
+    bool setData(const QModelIndex &index, const QVariant &value, int role) override;
     QVariant headerData(int section, Qt::Orientation orientation, int role) const override;
     Qt::ItemFlags flags(const QModelIndex &index) const override;