Fix cppcheck warnings

Signed-off-by: George Liu <liuxiwei@inspur.com>
Change-Id: I18be21d5141630a1da3d5e54740b54a9a06496d9
diff --git a/src/id_button.cpp b/src/id_button.cpp
index 71e8539..99fd27f 100644
--- a/src/id_button.cpp
+++ b/src/id_button.cpp
@@ -24,7 +24,8 @@
     pressed();
 }
 
-void IDButton::handleEvent(sd_event_source* es, int fd, uint32_t revents)
+void IDButton::handleEvent(sd_event_source* /* es */, int fd,
+                           uint32_t /* revents */)
 {
     int n = -1;
     char buf = '0';