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

Signed-off-by: Andrew Davis <afd@ti.com>
diff --git a/arch/arm/dts/keystone-k2l-evm.dts b/arch/arm/dts/keystone-k2l-evm.dts
index ca049ba..c80ac10 100644
--- a/arch/arm/dts/keystone-k2l-evm.dts
+++ b/arch/arm/dts/keystone-k2l-evm.dts
@@ -1,11 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
- * Copyright 2014 Texas Instruments, Inc.
- *
  * Keystone 2 Lamarr EVM device tree
  *
- * 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.
+ * Copyright (C) 2014-2017 Texas Instruments Incorporated - http://www.ti.com/
  */
 /dts-v1/;