Port TinyCAN plugin to the "Ex" API

The TinyCAN plugin at the moment uses a "standard" API. Therefore at the moment two limitations arise:

• Device enumeration with QCanBusDevice::availableDevices() always returns "can0.0"
• It is not possible to use more than one device simultaneous. The "Ex" API provides up to four devices, AFAIK

I already prepared a patch: https://codereview.qt-project.org/180832 but I had some problems that either receiving or transmitting frames did not work afterwards on Linux. I have not checked on Windows yet.