Spirit bugfixes: Was hanging occasionally because there was not mechanism to...

Spirit bugfixes:  Was hanging occasionally because there was not mechanism to restart the poll timer if poll was not performed because Spirit ws busy.  Fixed by not checking if Spirit is busy.  The TX poll can be performed asynchronouly while spirit is busy; any outgoing data will queued until Spirit is ready. Fixed handling of a timeout condition.  Failure to transmition to the TX state would fail (timeout) if in a race condition Spirit already committed to the RX state.  The driver needs to recover the state properly and avoid debug assertions in this event.