This may happen when the device discovery agent is quickly started and
stopped and started again. If the stop-start combination is happening
quicker than dbus can deliver the Discovering flag of the Adapter1
BlueZ interface, BlueZ's stop response will override the new start
discovery request.

Task-number: QTBUG-53715
Change-Id: I6a03fc525c7f390db009fc68a5313352ebba7f79
Reviewed-by: Frank Meerkoetter <frank.meerkoetter@basyskom.com>
Reviewed-by: Alex Blasche <alexander.blasche@theqtcompany.com>