mod_sysfs_setup() doesn't return errno when kobject_add_dir() failure occurs

mod_sysfs_setup() doesn't return an errno when kobject_add_dir() for module
"holders" directory fails.  So caller of mod_sysfs_setup() will keep going
and get oops.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>