Add support for communicating with modems exposed via QRTR on platforms like SDM845.
With devices like the OnePlus 6 and Xiaomi Pocophone F1 now running mainline Linux, the modem is booting successfully (and libqmi can read information like APN configurations). However ModemManager is not able to see it or communicate with it so it's not possible to make phone calls, send texts or setup a data connection.
The devices run postmarketOS amazingly and having a working modem would be a massive step towards being able to daily drive almost entirely FOSS software!