sysfs: fix /sys/module/*/holders after sysfs logic change

Sysfs symlinks now require fully registered kobjects as a target,
otherwise the call to create a symlink will fail. Here we register
the kobject before we request the symlink in the holders directory.

Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Cc: Tejun Heo <teheo@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>