Hack solution for aggregator recursive parts list (#6)

When trying to bridge composed devices (devices which functionality is
spread hierarchically over multiple endpoints) the aggregator needs to
know all endpoints including all children of all aggregated devices.

Normally we should use the `SetFlatCompositionForEndpoint` for this
purpose, yet this doesn't work as the endpoint needs to be deactivated
before setting the flat composition (recursive look up of children
endpoints).

Therefore we tell the system that all endpoints are flat composition.

This will become a problem when we have composed devices of multiple
depths levels. In that case we need to set thos devices to tree
composition or reset tree composition to the default and find a solution
how to set flat composition for the aggregator device type

src/app/util/attribute-storage.cpp

@@ -211,6 +211,7 @@ void emberAfEndpointConfigure()
         for (ep = FIXED_ENDPOINT_COUNT; ep < MAX_ENDPOINT_COUNT; ep++)
         {
             emAfEndpoints[ep] = EmberAfDefinedEndpoint();
+            emAfEndpoints[ep].bitmask.Set(EmberAfEndpointOptions::isFlatComposition);
         }
     }
 #endif