documentation: update s390 header file paths

Update Documentation/s390/ files to reflect changed header files
locations.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/s390/cds.txt b/Documentation/s390/cds.txt
index c4b7b2b..480a78e 100644
--- a/Documentation/s390/cds.txt
+++ b/Documentation/s390/cds.txt
@@ -98,7 +98,7 @@
 of them can be found on other Linux platforms implementations too.
 Miscellaneous function prototypes, data declarations, and macro definitions
 can be found in the architecture specific C header file
-linux/include/asm-s390/irq.h.
+linux/arch/s390/include/asm/irq.h.
 
 Overview of CDS interface concepts