Unify GPU plugin copyright headers

Now all are SPDX with LGPL2.1/3.0/EV

plugins/global/gpu/GpuPlugin.cpp

 /*
-    Copyright (c) 2020 Arjen Hiemstra <ahiemstra@heimr.nl>
-
-    This library is free software; you can redistribute it and/or
-    modify it under the terms of the GNU Library General Public
-    License as published by the Free Software Foundation; either
-    version 2 of the License, or (at your option) any later version.
-
-    This library is distributed in the hope that it will be useful,
-    but WITHOUT ANY WARRANTY; without even the implied warranty of
-    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-    Library General Public License for more details.
-
-    You should have received a copy of the GNU Library General Public License
-    along with this library; see the file COPYING.LIB.  If not, write to
-    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
-    Boston, MA 02110-1301, USA.
-*/
+ * SPDX-FileCopyrightText: 2020 Arjen Hiemstra <ahiemstra@heimr.nl>
+ *
+ * SPDX-License-Identifier: LGPL-2.1-only OR LGPL-3.0-only OR LicenseRef-KDE-Accepted-LGPL
+ */
 
 #include "GpuPlugin.h"
 

plugins/global/gpu/GpuPlugin.h

 /*
-    Copyright (c) 2020 Arjen Hiemstra <ahiemstra@heimr.nl>
-
-    This library is free software; you can redistribute it and/or
-    modify it under the terms of the GNU Library General Public
-    License as published by the Free Software Foundation; either
-    version 2 of the License, or (at your option) any later version.
-
-    This library is distributed in the hope that it will be useful,
-    but WITHOUT ANY WARRANTY; without even the implied warranty of
-    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-    Library General Public License for more details.
-
-    You should have received a copy of the GNU Library General Public License
-    along with this library; see the file COPYING.LIB.  If not, write to
-    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
-    Boston, MA 02110-1301, USA.
-*/
+ * SPDX-FileCopyrightText: 2020 Arjen Hiemstra <ahiemstra@heimr.nl>
+ *
+ * SPDX-License-Identifier: LGPL-2.1-only OR LGPL-3.0-only OR LicenseRef-KDE-Accepted-LGPL
+ */
 
 #pragma once
 

plugins/global/gpu/NvidiaSmiProcess.cpp

@@ -2,7 +2,7 @@
  * SPDX-FileCopyrightText: 2019 David Edmundson <davidedmundson@kde.org>
  * SPDX-FileCopyrightText: 2020 Arjen Hiemstra <ahiemstra@heimr.nl>
  *
- * SPDX-License-Identifier: LGPL-2.0-or-later
+ * SPDX-License-Identifier: LGPL-2.1-only OR LGPL-3.0-only OR LicenseRef-KDE-Accepted-LGPL
  */
 
 #include "NvidiaSmiProcess.h"

plugins/global/gpu/NvidiaSmiProcess.h

 /*
  * SPDX-FileCopyrightText: 2020 Arjen Hiemstra <ahiemstra@heimr.nl>
- * 
- * SPDX-License-Identifier: LGPL-2.0-or-later
+ *
+ * SPDX-License-Identifier: LGPL-2.1-only OR LGPL-3.0-only OR LicenseRef-KDE-Accepted-LGPL
  */
 
 #pragma once