mkt settings binding must use libqofono modeminterface

[Jonas G. Drange]

From r66 of nemomobile's libqofono lib all the bindings subclass the ofonomodem interface, which correctly handles interfaces going away, coming back, etc.

2) Libqofono version 0.53 and 0.70
3) What you expected to happen
When removing the mtk interface from the modem and re-adding it, I expected mtk binding to still function

4) What happened instead
Mtk binding does not function