Explictly set firmware pointer to nullptr on unload.Prevents crash if user trys…

Authored by rizzitello on Nov 2 2018, 7:46 PM.

Description

Explictly set firmware pointer to nullptr on unload.Prevents crash if user trys to reconnect before the pluin is fully unloaded.

Signed-off-by: Chris Rizzitello <rizzitello@kde.org>