pinctrl: meson-axg: Use the correct style for SPDX License Identifier

This patch corrects the SPDX License Identifier style in
header file related Meson axg SoC pinctrl driver.
It assigns explicit block comment for the SPDX License Identifier.

Changes made by using a script provided by Joe Perches here:
https://lkml.org/lkml/2019/2/7/46.
Suggested-by: Joe Perches <joe@perches.com>
Signed-off-by: Nishad Kamdar <nishadkamdar@gmail.com>
Link: https://lore.kernel.org/r/bcb86aa22d8d8499502bbd8c54a364be24886a86.1574871463.git.nishadkamdar@gmail.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/meson/pinctrl-meson-axg-pmx.h

+/* SPDX-License-Identifier: (GPL-2.0+ or MIT) */
 /*
  * Copyright (c) 2017 Baylibre SAS.
  * Author:  Jerome Brunet  <jbrunet@baylibre.com>
@@ -5,7 +6,6 @@
  * Copyright (c) 2017 Amlogic, Inc. All rights reserved.
  * Author: Xingyu Chen <xingyu.chen@amlogic.com>
  *
- * SPDX-License-Identifier: (GPL-2.0+ or MIT)
  */
 
 struct meson_pmx_bank {