scenery: Remove redundant setting the property root.

The same value was extracted out of the same options value
in the code above. So, skip resetting to the same value.

simgear/scene/model/SGReaderWriterXML.cxx

@@ -263,8 +263,6 @@ sgLoad3DModel_internal(const SGPath& path,
         // model without wrapper
     }
 
-    options->setPropertyNode(prop_root);
-    
     // Assume that textures are in
     // the same location as the XML file.
     if (!model) {