driver core: sysdev: do not send KOBJ_ADD uevent if kobject_init_and_add fails

If kobject_init_and_add fails, sysdev_register should not send KOBJ_ADD
uevent to userspace.

Signed-off-by: Xiaotian Feng <dfeng@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>