scsi-disk: Track tray open/close state

We already track it in BlockDriverState since commit 4be9762a.  As
discussed in that commit's message, we should track it in the device
device models instead, because it's device state.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

hw/scsi-disk.c

@@ -72,6 +72,7 @@ struct SCSIDiskState
     QEMUBH *bh;
     char *version;
     char *serial;
+    bool tray_open;
 };
 
 static int scsi_handle_rw_error(SCSIDiskReq *r, int error, int type);
@@ -823,6 +824,7 @@ static void scsi_disk_emulate_start_stop(SCSIDiskReq *r)
 
     if (s->qdev.type == TYPE_ROM && loej) {
         bdrv_eject(s->bs, !start);
+        s->tray_open = !start;
     }
 }