SPDX: fix IBM-pibs license identifier

The SPDX License List version 1.19 now contains an official entry for
the IBM-pibs license.  However, instead of our suggestion "ibm-pibs",
the SPDX License List uses "IBM-pibs", with the following rationale:
"The reason being that all other SPDX License List short identifiers
tend towards using capital letters unless spelling a word.  I'd prefer
to be consistent to this end".

Change the license IDs to use the official name.

Signed-off-by: Wolfgang Denk <wd@denx.de>
diff --git a/arch/powerpc/cpu/ppc4xx/4xx_pci.c b/arch/powerpc/cpu/ppc4xx/4xx_pci.c
index 5584e0f..08781a1 100644
--- a/arch/powerpc/cpu/ppc4xx/4xx_pci.c
+++ b/arch/powerpc/cpu/ppc4xx/4xx_pci.c
@@ -1,5 +1,5 @@
 /*
- * SPDX-License-Identifier:	GPL-2.0	ibm-pibs
+ * SPDX-License-Identifier:	GPL-2.0	IBM-pibs
  *
  *  File Name:   405gp_pci.c
  *
diff --git a/arch/powerpc/cpu/ppc4xx/4xx_uart.c b/arch/powerpc/cpu/ppc4xx/4xx_uart.c
index 50c28a0..c02058f 100644
--- a/arch/powerpc/cpu/ppc4xx/4xx_uart.c
+++ b/arch/powerpc/cpu/ppc4xx/4xx_uart.c
@@ -5,7 +5,7 @@
  * (C) Copyright 2010
  * Stefan Roese, DENX Software Engineering, sr@denx.de.
  *
- * SPDX-License-Identifier:	GPL-2.0	ibm-pibs
+ * SPDX-License-Identifier:	GPL-2.0	IBM-pibs
  */
 
 #include <common.h>
diff --git a/arch/powerpc/cpu/ppc4xx/miiphy.c b/arch/powerpc/cpu/ppc4xx/miiphy.c
index e4a9db6..10147de 100644
--- a/arch/powerpc/cpu/ppc4xx/miiphy.c
+++ b/arch/powerpc/cpu/ppc4xx/miiphy.c
@@ -1,5 +1,5 @@
 /*
- * SPDX-License-Identifier:	GPL-2.0	ibm-pibs
+ * SPDX-License-Identifier:	GPL-2.0	IBM-pibs
  */
 /*-----------------------------------------------------------------------------+
   |
diff --git a/arch/powerpc/cpu/ppc4xx/start.S b/arch/powerpc/cpu/ppc4xx/start.S
index d9d8cbf..38bbc5a 100644
--- a/arch/powerpc/cpu/ppc4xx/start.S
+++ b/arch/powerpc/cpu/ppc4xx/start.S
@@ -6,7 +6,7 @@
  *  Copyright (c) 2008 Nuovation System Designs, LLC
  *    Grant Erickson <gerickson@nuovations.com>
  *
- * SPDX-License-Identifier:	GPL-2.0	ibm-pibs
+ * SPDX-License-Identifier:	GPL-2.0	IBM-pibs
  */
 
 /*