docbook: fix s390 fatal error after header files moved

Fix (fatal error) s390 docbook file to handle renamed header files.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>