For those who don't care about the QMI support through libqmi-glib, or if you're
stuck with glib 2.30 (libqmi-glib requires 2.32), this configure switch allows
disabling the QMI support completely.
The logic to detect cdc-wdm ports is still in place, but the QMI probing is
never launched at them. Also, all QMI-related objects won't be compiled.