SPDX: Convert all of our single license tags to Linux Kernel style

When U-Boot started using SPDX tags we were among the early adopters and
there weren't a lot of other examples to borrow from.  So we picked the
area of the file that usually had a full license text and replaced it
with an appropriate SPDX-License-Identifier: entry.  Since then, the
Linux Kernel has adopted SPDX tags and they place it as the very first
line in a file (except where shebangs are used, then it's second line)
and with slightly different comment styles than us.

In part due to community overlap, in part due to better tag visibility
and in part for other minor reasons, switch over to that style.

This commit changes all instances where we have a single declared
license in the tag as both the before and after are identical in tag
contents.  There's also a few places where I found we did not have a tag
and have introduced one.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/include/asm-generic/global_data.h b/include/asm-generic/global_data.h
index c16ad73..2d451f8 100644
--- a/include/asm-generic/global_data.h
+++ b/include/asm-generic/global_data.h
@@ -1,9 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * Copyright (c) 2012 The Chromium OS Authors.
  * (C) Copyright 2002-2010
  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
- *
- * SPDX-License-Identifier:	GPL-2.0+
  */
 
 #ifndef __ASM_GENERIC_GBL_DATA_H
diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
index bf230c1..d036026 100644
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -1,7 +1,7 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * Copyright (c) 2011 The Chromium OS Authors.
  * Copyright (c) 2011, NVIDIA Corp. All rights reserved.
- * SPDX-License-Identifier:	GPL-2.0+
  */
 
 #ifndef _ASM_GENERIC_GPIO_H_
diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index 0f5160c..7a2f0db 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -1,9 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * Generic I/O functions.
  *
  * Copyright (c) 2016 Imagination Technologies Ltd.
- *
- * SPDX-License-Identifier:	GPL-2.0+
  */
 
 #ifndef __ASM_GENERIC_IO_H__
diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
index b653570..296c0cf 100644
--- a/include/asm-generic/sections.h
+++ b/include/asm-generic/sections.h
@@ -1,7 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * Copyright (c) 2011 The Chromium OS Authors.
- *
- * SPDX-License-Identifier:	GPL-2.0+
  */
 
 /* Taken from Linux kernel, commit f56c3196 */
diff --git a/include/asm-generic/u-boot.h b/include/asm-generic/u-boot.h
index f734d53..eee84f4 100644
--- a/include/asm-generic/u-boot.h
+++ b/include/asm-generic/u-boot.h
@@ -1,10 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * Copyright (c) 2011 The Chromium OS Authors.
  *
  * (C) Copyright 2000 - 2002
  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
- *
- * SPDX-License-Identifier:	GPL-2.0+
  ********************************************************************
  * NOTE: This header file defines an interface to U-Boot. Including
  * this (unmodified) header file in another file is considered normal