Cleanup from the Qt5 dependences

Now in this branch there is QtSerialPort which has support only for Qt4.

Change-Id: I11d5403dcc17f8c2929429abb6df9f2b2b4fb558
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Reviewed-by: Sergey Belyashov <Sergey.Belyashov@gmail.com>