Fix cppcheck warnings

Signed-off-by: George Liu <liuxiwei@inspur.com>
Change-Id: I18be21d5141630a1da3d5e54740b54a9a06496d9
diff --git a/inc/button_interface.hpp b/inc/button_interface.hpp
index 0a0181b..9d85e8e 100644
--- a/inc/button_interface.hpp
+++ b/inc/button_interface.hpp
@@ -108,8 +108,8 @@
         }
     }
 
-    buttonConfig config;
     sdbusplus::bus::bus& bus;
     EventPtr& event;
+    buttonConfig config;
     sd_event_io_handler_t callbackHandler;
 };