Removed constant debugging output from scanning for serial ports.

Replaced with only 1 output message with the result of the first serial port scan.

If you don't have anything connected, you get a long stream of messages like "No Ports Found". This can be annoying if QGC has sat around for a while, as you may not be able to scroll back up to see any other debugging messages that were output at startup. I see no reason to keep these messages, so I've removed them and replaced them with a single message indicating if no serial ports were found.