[loxone] fix representation property (openhab#10086)

Signed-off-by: Jan N. Klug <[email protected]>
Signed-off-by: John Marshall <[email protected]>

bundles/org.openhab.binding.loxone/src/main/java/org/openhab/binding/loxone/internal/LxDiscoveryParticipant.java

@@ -71,7 +71,7 @@ public DiscoveryResult createResult(RemoteDevice device) {
             properties.put(Thing.PROPERTY_SERIAL_NUMBER, serial);
 
             return DiscoveryResultBuilder.create(uid).withProperties(properties).withLabel(label)
-                    .withRepresentationProperty(serial).build();
+                    .withRepresentationProperty(Thing.PROPERTY_SERIAL_NUMBER).build();
         }
         return null;
     }