ARM: sunxi: Add a missing SPDX license header

Add the missing SPDX license header to arch/arm/mach-sunxi/sunxi.c.
Signed-off-by: Jason Wang <wangborong@cdjrlc.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20210810132954.107518-1-wangborong@cdjrlc.com

arch/arm/mach-sunxi/sunxi.c

+// SPDX-License-Identifier: GPL-2.0
 /*
  * Device Tree support for Allwinner A1X SoCs
  *
@@ -5,9 +6,6 @@
  *
  * Maxime Ripard <maxime.ripard@free-electrons.com>
  *
- * This file is licensed under the terms of the GNU General Public
- * License version 2.  This program is licensed "as is" without any
- * warranty of any kind, whether express or implied.
  */
 
 #include <linux/clocksource.h>