I believe this is true on the Mavic, but if you look at the user guide for the Spark RC, the device connects to the controller via Wi-Fi. There is no USB port on the Spark RC.
There is a micro-USB port on the Spark controller, it is currently used for charging and as far as we know at the moment, it is going to be used for the goggles, but not for the phone/tablet connection.
The controller manual shows the port in the bottom, same place as the Mavic has its second USB port.