Avoid calling write in inactive state

[christophfroehlich]

After looking at the code, I believe this is happening because we call the write method also for the inactive components
https://github.com/ros-controls/ros2_control/blob/master/hardware_interface%2Fsrc%2Fsystem.cpp#L247 and https://github.com/ros-controls/ros2_control/blob/master/hardware_interface%2Fsrc%2Factuator.cpp#L251

If we need to properly fix it, I think we might need a new method called dynamic_configure where all the gpio interfaces go in and then the main hardware command interfaces can go in the write method, in this way we can call this new dynamic_configure method and avoid calling write method in the inactive state.

Originally posted by @saikishor in ros-controls/ros2_control_demos#455 (comment)