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-k2g-ice.dts b/arch/arm/dts/keystone-k2g-ice.dts
index ecca2df..2ed657e 100644
--- a/arch/arm/dts/keystone-k2g-ice.dts
+++ b/arch/arm/dts/keystone-k2g-ice.dts
@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: GPL-2.0+
+// SPDX-License-Identifier: GPL-2.0
 /*
  * Device Tree Source for K2G Industrial Communication Engine EVM
  *