WWAN interfaces still need ifname in device model

[eriknordmark]

Please provide information requested in the template below as much as possible.

Describe the bug

The commit message and code in 65852ac intended to allow for WWAN interfaces to be indenfied by a PCI address or USB address in order to handle the dynamic and random order the wwan interfaces might be numbered by the kernel.

However, for management ports (and potentially for app-shared ports as well) we do need to determine the kernel ifname before we can interact with the kernel/dhcpcd (e.g., to configure the kernel netlink and IP addresses), and for the logic in zedcloud/send.go to send requests to the controller using a particular interface. That type of logic would need to use the PCI address, USB address, or USB prod to determine the ifname dynamically.

Without this we see errors in the logs of the form "missing interface name" from SendOnIntf()