arm64: Use the correct style for SPDX License Identifier

This patch corrects the SPDX License Identifier style
in the arm64 Hardware Architecture related files.
Suggested-by: NJoe Perches <joe@perches.com>
Signed-off-by: NNishad Kamdar <nishadkamdar@gmail.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

arch/arm64/boot/dts/mediatek/mt2712-pinfunc.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2018 MediaTek Inc.
  * Author: Zhiyong Tao <zhiyong.tao@mediatek.com>

arch/arm64/include/asm/pointer_auth.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef __ASM_POINTER_AUTH_H
 #define __ASM_POINTER_AUTH_H
 

arch/arm64/include/asm/sdei.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 // Copyright (C) 2017 Arm Ltd.
 #ifndef __ASM_SDEI_H
 #define __ASM_SDEI_H

arch/arm64/include/asm/vmap_stack.h

-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 // Copyright (C) 2017 Arm Ltd.
 #ifndef __ASM_VMAP_STACK_H
 #define __ASM_VMAP_STACK_H