staging: lustre: remove parentheses usage with return

Fix the following checkpatch error:

ERROR: return is not a function, parentheses are not required
Signed-off-by: Srikrishan Malik <srikrishanmalik@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/mdc/mdc_request.c

@@ -2588,7 +2588,7 @@ static int mdc_process_config(struct obd_device *obd, obd_count len, void *buf)
 			rc = 0;
 		break;
 	}
-	return(rc);
+	return rc;
 }