SPDX-License-Identifier: convert PIBS licensed files

This commit adapts the files that were derived from PIBS (PowerPC
Initialization and Boot Software) codeto using SPDX License
Identifiers.

So far, SPDX has not assigned an official License ID for the PIBS
license yet, so this should be considered preliminary.

Note that the following files contained incorrect license information:

	arch/powerpc/cpu/ppc4xx/4xx_uart.c
	arch/powerpc/cpu/ppc4xx/start.S
	arch/powerpc/include/asm/ppc440.h

These files included, in addition to the GPL-2.0 / ibm-pibs dual
license as inherited from PIBS, a GPL-2.0+ license header which was
obviously incorrect.  This has been removed.

Signed-off-by: Wolfgang Denk <wd@denx.de>
Cc: Stefan Roese <sr@denx.de>
Signed-off-by: Wolfgang Denk <wd@denx.de>

Conflicts:
	Licenses/README
Acked-by: Stefan Roese <sr@denx.de>
diff --git a/board/csb472/init.S b/board/csb472/init.S
index e00b5f5..f5805b7 100644
--- a/board/csb472/init.S
+++ b/board/csb472/init.S
@@ -1,26 +1,6 @@
-/******************************************************************************
- *   This source code is dual-licensed.  You may use it under the terms of the
- *   GNU General Public License version 2, or under the license below.
- *
- *	 This source code has been made available to you by IBM on an AS-IS
- *	 basis.	 Anyone receiving this source is licensed under IBM
- *	 copyrights to use it in any way he or she deems fit, including
- *	 copying it, modifying it, compiling it, and redistributing it either
- *	 with or without modifications.	 No license under IBM patents or
- *	 patent applications is to be implied by the copyright license.
- *
- *	 Any user of this software should understand that IBM cannot provide
- *	 technical support for this software and will not be responsible for
- *	 any consequences resulting from the use of this software.
- *
- *	 Any person who transfers this source code or any derivative work
- *	 must include the IBM copyright notice, this paragraph, and the
- *	 preceding two paragraphs in the transferred software.
- *
- *	 COPYRIGHT   I B M   CORPORATION 1995
- *	 LICENSED MATERIAL  -  PROGRAM PROPERTY OF I B M
- *
- *****************************************************************************/
+/*
+ * SPDX-License-Identifier:	GPL-2.0	ibm-pibs
+ */
 #include <config.h>
 #include <asm/ppc4xx.h>