scsi-bus: use DO_UPCAST

Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

hw/scsi-bus.c

diff --git a/hw/scsi-bus.c b/hw/scsi-bus.c
index 0b0344c..d1ef559 100644
--- a/hw/scsi-bus.c
+++ b/hw/scsi-bus.c
@@ -725,7 +725,7 @@
 
 static char *scsibus_get_fw_dev_path(DeviceState *dev)
 {
-    SCSIDevice *d = (SCSIDevice*)dev;
+    SCSIDevice *d = DO_UPCAST(SCSIDevice, qdev, dev);
     SCSIBus *bus = scsi_bus_from_device(d);
     char path[100];
     int i;