Remove unnecessary attribute

Author: hacker1024

app/src/main/res/menu/menu_activity_main.xml

@@ -15,7 +15,6 @@
         app:showAsAction="ifRoom" />
     <item
         android:id="@+id/settingsItem"
-        android:checkable="false"
         android:icon="@drawable/ic_settings_24dp"
         android:title="@string/item_settings_menu_activity_main"
         app:showAsAction="never" />