ofono: Find a way to have consistent paths for modems
Currently, paths for modem seems to be of the type "/" + modem_type + index (eg /sierra_1), where the index is calculated in way in which usually the same index is given to the same modem, but if the modem is re-plugged while ofono is running, then that modem re-appears in ofono with a new index.
In osmo-gsm-tester, we depend on the modem dbus path to identify them, and we require the path to stay the same as it's hardcoded in the config.
There should be some way by means of udev to gather some config specific for each modem (eg. usb device id), and use that instead of an increasing index. This way the path would remain stable. That would be the default name (eg. (/gobi_05c6_9215), but some udev rules could be applied to add a MODEM_NAME attribute to have any name for a path, (eg: /gobi_970010202, where the number is the imsi we know it is using).
I think this type of patch is going to be welcome in upstream if not yet available, and will free us from a lot of errors during tests.