sd: delay calling free_opal_dev

sd: delay calling free_opal_dev

Call free_opal_dev from scsi_disk_release as the opal_dev field is accessed
from the ioctl handler, which isn't synchronized vs sd_release and thus
can be accessed during or after sd_release was called.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>