openocd: fix SPDX tag format for files .c

With the old checkpatch we cannot use the correct format for the
SPDX tags in the file .c, in fact the C99 comments are not allowed
and we had to use the block comment.

With the new checkpatch, let's switch to the correct SPDX format.

Change created automatically through the command:
	sed -i \
	's,^/\* *\(SPDX-License-Identifier: .*[^ ]\) *\*/$,// \1,' \
	$(find src/ contrib/ -name \*.c)

Change-Id: I6da16506baa7af718947562505dd49606d124171
Signed-off-by: Antonio Borneo <[email protected]>
Reviewed-on: https://review.openocd.org/c/openocd/+/7153
Tested-by: jenkins

Author: borneoa

contrib/itmdump.c

@@ -1,4 +1,4 @@
-/* SPDX-License-Identifier: GPL-3.0-or-later */
+// SPDX-License-Identifier: GPL-3.0-or-later
 
 /* Copyright (C) 2010 by David Brownell */
 

contrib/libdcc/dcc_stdio.c

@@ -1,4 +1,4 @@
-/* SPDX-License-Identifier: GPL-2.0-or-later */
+// SPDX-License-Identifier: GPL-2.0-or-later
 
 /***************************************************************************
  *   Copyright (C) 2008 by Dominic Rath                                    *

contrib/libdcc/example.c

@@ -1,4 +1,4 @@
-/* SPDX-License-Identifier: GPL-2.0-or-later */
+// SPDX-License-Identifier: GPL-2.0-or-later
 
 /***************************************************************************
  *   Copyright (C) 2008 by Spencer Oliver                                  *

contrib/list_example.c

@@ -1,4 +1,4 @@
-/* SPDX-License-Identifier: GPL-2.0-or-later */
+// SPDX-License-Identifier: GPL-2.0-or-later
 /* Copyright (C) 2021 by Andreas Fritiofson <[email protected]> */
 
 /*

contrib/loaders/checksum/riscv_crc.c

@@ -1,4 +1,4 @@
-/* SPDX-License-Identifier: GPL-2.0-or-later */
+// SPDX-License-Identifier: GPL-2.0-or-later
 
 /* Copyright (C) 2009-2021 Free Software Foundation, Inc. */
 

contrib/loaders/flash/at91sam7x/dcc.c

@@ -1,4 +1,4 @@
-/* SPDX-License-Identifier: GPL-2.0-or-later */
+// SPDX-License-Identifier: GPL-2.0-or-later
 
 /***************************************************************************
  *   Copyright (C) 2007 by Pavel Chromy                                    *

contrib/loaders/flash/at91sam7x/main.c

@@ -1,4 +1,4 @@
-/* SPDX-License-Identifier: GPL-2.0-or-later */
+// SPDX-License-Identifier: GPL-2.0-or-later
 
 /***************************************************************************
  *   Copyright (C) 2007 by Pavel Chromy                                    *

contrib/loaders/flash/at91sam7x/samflash.c

@@ -1,4 +1,4 @@
-/* SPDX-License-Identifier: GPL-2.0-or-later */
+// SPDX-License-Identifier: GPL-2.0-or-later
 
 /***************************************************************************
  *   Copyright (C) 2007 by Pavel Chromy                                    *

contrib/loaders/flash/bluenrg-x/bluenrg-x_write.c

@@ -1,4 +1,4 @@
-/* SPDX-License-Identifier: GPL-2.0-or-later */
+// SPDX-License-Identifier: GPL-2.0-or-later
 
 /* To be built with arm-none-eabi-gcc -c -mthumb -mcpu=cortex-m0 -O3 bluenrgx.c */
 /* Then postprocess output of command "arm-none-eabi-objdump -d bluenrgx.o" to make a C array of bytes */

contrib/loaders/flash/cc26xx/flash.c

@@ -1,4 +1,4 @@
-/* SPDX-License-Identifier: BSD-3-Clause */
+// SPDX-License-Identifier: BSD-3-Clause
 
 /******************************************************************************
 *