block: Don't call bdrv_eject() if the tray state didn't change

It's not needed. Besides we can then assume that bdrv_eject() is
only called when there's a tray state change, which is useful to
the DEVICE_TRAY_MOVED event (going to be added in a future
commit).
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Acked-by: NKevin Wolf <kwolf@redhat.com>

hw/ide/atapi.c

@@ -883,8 +883,11 @@ static void cmd_start_stop_unit(IDEState *s, uint8_t* buf)
             ide_atapi_cmd_error(s, sense, ASC_MEDIA_REMOVAL_PREVENTED);
             return;
         }
-        bdrv_eject(s->bs, !start);
-        s->tray_open = !start;
+
+        if (s->tray_open != !start) {
+            bdrv_eject(s->bs, !start);
+            s->tray_open = !start;
+        }
     }
 
     ide_atapi_cmd_ok(s);

hw/scsi-disk.c

@@ -1050,8 +1050,11 @@ static int scsi_disk_emulate_start_stop(SCSIDiskReq *r)
                                  : SENSE_CODE(NOT_READY_REMOVAL_PREVENTED));
             return -1;
         }
-        bdrv_eject(s->qdev.conf.bs, !start);
-        s->tray_open = !start;
+
+        if (s->tray_open != !start) {
+            bdrv_eject(s->qdev.conf.bs, !start);
+            s->tray_open = !start;
+        }
     }
     return 0;
 }