opt: add config parse arg num to 4

protocols/dwl-ipc-unstable-v2.xml

@@ -172,6 +172,8 @@ I would probably just submit raphi's patchset but I don't think that would be po
       <arg name="dispatch" type="string" summary="dispatch name."/>
       <arg name="arg1" type="string" summary="arg1."/>
       <arg name="arg2" type="string" summary="arg2."/>
+      <arg name="arg3" type="string" summary="arg3."/>
+      <arg name="arg4" type="string" summary="arg4."/>
     </request>
 
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