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/board/zyxel/nsa310s/Kconfig b/board/zyxel/nsa310s/Kconfig
index 77e734d..801d696 100644
--- a/board/zyxel/nsa310s/Kconfig
+++ b/board/zyxel/nsa310s/Kconfig
@@ -1,10 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0+
 #
 # Copyright (C) 2015
 # Gerald Kerma <dreagle@doukki.net>
 # Tony Dinh <mibodhi@gmail.com>
-#
-# SPDX-License-Identifier:	GPL-2.0+
-#
 
 if TARGET_NSA310S
 
diff --git a/board/zyxel/nsa310s/Makefile b/board/zyxel/nsa310s/Makefile
index 43cdb86..2131e28 100644
--- a/board/zyxel/nsa310s/Makefile
+++ b/board/zyxel/nsa310s/Makefile
@@ -1,9 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0+
 #
 # Copyright (C) 2015
 # Gerald Kerma <dreagle@doukki.net>
 # Tony Dinh <mibodhi@gmail.com>
-#
-# SPDX-License-Identifier:	GPL-2.0+
-#
 
 obj-y	:= nsa310s.o
diff --git a/board/zyxel/nsa310s/kwbimage.cfg b/board/zyxel/nsa310s/kwbimage.cfg
index e8f4b8a..9ebdeab 100644
--- a/board/zyxel/nsa310s/kwbimage.cfg
+++ b/board/zyxel/nsa310s/kwbimage.cfg
@@ -1,10 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0+
 #
 # Copyright (C) 2015
 # Gerald Kerma <dreagle@doukki.net>
 # Tony Dinh <mibodhi@gmail.com>
-#
-# SPDX-License-Identifier:	GPL-2.0+
-#
 # Refer to doc/README.kwbimage for more details about how-to
 # configure and create kirkwood boot images.
 #
diff --git a/board/zyxel/nsa310s/nsa310s.c b/board/zyxel/nsa310s/nsa310s.c
index aab33cf..e7cb6be 100644
--- a/board/zyxel/nsa310s/nsa310s.c
+++ b/board/zyxel/nsa310s/nsa310s.c
@@ -1,9 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0+
 /*
  * Copyright (C) 2015
  * Gerald Kerma <dreagle@doukki.net>
  * Tony Dinh <mibodhi@gmail.com>
- *
- * SPDX-License-Identifier:	GPL-2.0+
  */
 
 #include <common.h>
diff --git a/board/zyxel/nsa310s/nsa310s.h b/board/zyxel/nsa310s/nsa310s.h
index 1ea1105..d8bd9a5 100644
--- a/board/zyxel/nsa310s/nsa310s.h
+++ b/board/zyxel/nsa310s/nsa310s.h
@@ -1,9 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * Copyright (C) 2015
  * Gerald Kerma <dreagle@doukki.net>
  * Tony Dinh <mibodhi@gmail.com>
- *
- * SPDX-License-Identifier:	GPL-2.0+
  */
 
 #ifndef __NSA310S_H