Sierra EM7455 not recognized

[Tomek Mańko]

I know it's not strictly MM-related, but I couldn't find any answer elsewhere
so far, and since you're the guys who are developing MM you probably will have
some idea of what happens before the modem gets handed over to MM.
Hopefully it's okay.

So my workplace bought some Lenovos L460 which are supposed to have Sierra
Wireless EM7455 modems built-in (and indeed it does have a sim slot on the
right side), but neither `lsusub` nor `usb-devices` seem to report any device
with VID/PID 1199:9079 this modem is supposed to have. Manually `modprobe`ing
WWAN-related drivers like `wcserial`, `cdc_wdm` or `cdc_mbim` doesn't cause any
 new device to be recognised (I have no `/dev/cdc-wdm`, `/dev/ttyACM` nor
 `/dev/ttyUSB` files and `dmesg` only reports the module loading message).

I'm kinda confused since I've seen people using this modem (even on the same
Lenovo laptop model) and complaining it can't connect due to the QMI/MBIM
issue, but then they apparently must have the device visible in `/dev` without
any/much effort since otherwise I would've read about that.

Is there anything you would suggest to verify if the modem is broken and the
laptop needs replacement or even better yet enable it somehow?