AdvancedDockingSystem: Fix file licenses

Amends a7956df3ca which accidentally dropped the (L)GPL part.

Change-Id: I22e3f5cdb12b15ee777524cac04aa888606026c3
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/libs/advanceddockingsystem/dockwidget.cpp

@@ -1,5 +1,5 @@
 // Copyright (C) 2020 Uwe Kindler
-// SPDX-License-Identifier: LicenseRef-Qt-Commercial
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-2.1-or-later OR GPL-3.0-or-later
 
 #include "dockwidget.h"