[PATCH] s390: invalid check after kzalloc()

Typo.  After the call to kzalloc() for kdb->key_maps the test for NULL checks
the wrong variable.

Signed-off-by: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>