plugins: mtk: Added MT6229 USB modem support.
This modem is used for instance on the CAT B100 phone.
The phone modem was not detected by ModemManager on Debian Trixie (the current testing).
With the few lines added by this commit the modem was successfully detected (by mmcli
and by the NetworkManager user interface).
I could then configure a working broadband connection and connect to the internet.