cciss: Remove sysfs entries for logical drives on driver cleanup.

Sysfs entries for logical drives need to be removed when a drive is
deleted during driver cleanup.

Signed-off-by: Andrew Patterson <andrew.patterson@hp.com>
Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Acked-by: Mike Miller <mike.miller@hp.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>