fix: less logging from serial retries (#1030)
fix: less logging from serial retries (#1030)

After this change only the first error related to each configured
serialport is logged to stderr. If the port is connected then
the first error is logged again. Errors related to retries
are logged only on debug level, with debug key signalk:serialport.
SignalK/signalk-server-node,SignalK/signalk-server-node,SignalK/signalk-server-node,SignalK/signalk-server-node