s390: Use generic posix_types.h

Change the s390 architecture to use <asm-generic/posix_types.h>.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Link: http://lkml.kernel.org/r/1328677745-20121-17-git-send-email-hpa@zytor.com
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: <linux390@de.ibm.com>