[PATCH] fix audit_krule_to_{rule,data} return values

Don't return -ENOMEM when callers of these functions are checking for
a NULL return.  Bug noticed by Serge Hallyn.

Signed-off-by: Amy Griffis <amy.griffis@hp.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>