scsi: scsi_transport_fc: fix NULL pointer dereference in fc_bsg_job_timeout

bsg-lib now embeddeds the job structure into the request, and
req->special can't be used anymore.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: stable@vger.kernel.org
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/scsi_transport_fc.c

@@ -3571,7 +3571,7 @@ fc_vport_sched_delete(struct work_struct *work)
 static enum blk_eh_timer_return
 fc_bsg_job_timeout(struct request *req)
 {
-	struct bsg_job *job = (void *) req->special;
+	struct bsg_job *job = blk_mq_rq_to_pdu(req);
 	struct Scsi_Host *shost = fc_bsg_to_shost(job);
 	struct fc_rport *rport = fc_bsg_to_rport(job);
 	struct fc_internal *i = to_fc_internal(shost->transportt);