[PATCH] fix rescan warning

The prototype for scsi_rescan_device was missing and once added it's
caller doesn't compile anymore because it expects a return value..

drivers/scsi/scsi.h

@@ -442,6 +442,7 @@ extern void scsi_finish_command(Scsi_Cmnd *);
 extern int scsi_retry_command(Scsi_Cmnd *);
 extern int scsi_attach_device(struct scsi_device *);
 extern void scsi_detach_device(struct scsi_device *);
+extern void scsi_rescan_device(struct scsi_device *);
 extern int scsi_get_device_flags(unsigned char *vendor, unsigned char *model);
 
 /*

drivers/scsi/scsi_sysfs.c

@@ -275,12 +275,8 @@ show_rescan_field (struct device *dev, char *buf)
 static ssize_t
 store_rescan_field (struct device *dev, const char *buf, size_t count) 
 {
-	int ret = ENODEV;
-	struct scsi_device *sdev;
-	sdev = to_scsi_device(dev);
-	if (sdev)
-		ret = scsi_rescan_device(sdev);
-	return ret;
+	scsi_rescan_device(to_scsi_device(dev));
+	return 0;
 }
 
 static DEVICE_ATTR(rescan, S_IRUGO | S_IWUSR, show_rescan_field, store_rescan_field)