arm: dts: am3x: Update devicetree header comments to sync with v6.3-rc6

Signed-off-by: Andrew Davis <afd@ti.com>
diff --git a/arch/arm/dts/am335x-phycore-som.dtsi b/arch/arm/dts/am335x-phycore-som.dtsi
index 8d7c19e..3b4b97a 100644
--- a/arch/arm/dts/am335x-phycore-som.dtsi
+++ b/arch/arm/dts/am335x-phycore-som.dtsi
@@ -1,11 +1,7 @@
-// SPDX-License-Identifier: GPL-2.0
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (C) 2015 Phytec Messtechnik GmbH
  * Author: Teresa Remmet <t.remmet@phytec.de>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
  */
 
 #include "am33xx.dtsi"