cciss: Add lunid attribute to each logical drive in /sys

Add lunid attribute to each logical drive at
/sys/devices/<dev>/ccissX/cXdY/lunid for controller X,
logical drive Y

Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>