[SCSI] zfcp: Call get_device on port before calling put_device

zfcp_unit_release calls put_device on the port. Ensure that get_device
has been called before possibly triggering the release function
through put_device or device_unregister.
Reviewed-by: NSwen Schillig <swen@vnet.ibm.com>
Signed-off-by: NChristof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: NJames Bottomley <James.Bottomley@suse.de>

drivers/s390/scsi/zfcp_unit.c

@@ -142,6 +142,8 @@ int zfcp_unit_add(struct zfcp_port *port, u64 fcp_lun)
 		return -ENOMEM;
 	}
 
+	get_device(&port->dev);
+
 	if (device_register(&unit->dev)) {
 		put_device(&unit->dev);
 		return -ENOMEM;
@@ -152,8 +154,6 @@ int zfcp_unit_add(struct zfcp_port *port, u64 fcp_lun)
 		return -EINVAL;
 	}
 
-	get_device(&port->dev);
-
 	write_lock_irq(&port->unit_list_lock);
 	list_add_tail(&unit->list, &port->unit_list);
 	write_unlock_irq(&port->unit_list_lock);