docbook: rapidio: fix fatal filename error

Fix docbook fatal error (files were renamed):
docproc: linux-2.6.24-git9/arch/ppc/kernel/rio.c: No such file or directory

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>