If the device is not showing up with "lsusb" then the device is either not connected, not connected via USB, or perhaps has not been powered up (might need something toggled during boot or a dedicated regulator to be described) as the output of the command is a raw read of the devices attached to the USB bus and there is no need for anything to be "supported" with drivers etc.
NB: device-tree will only describe the connectivity for the USB hub/ports, there's no need to describe attached USB devices because once ports are probed/discovered anything attached to them will be probed and have supported drivers loaded automatically (as it's USB). Asmedia chips are normally supported by the generic "CONFIG_USB_UAS" driver which is enabled by default in LE images; and I would assume in ilmich images too.
Pastebin the dumped device-tree file, someone else might see something in it.