The Firmware interface was highly based on 'slots' to identify the existing
firmware images; but that doesn't fit very well with the initial implementation
of the Firmware interface in QMI-based modems. In these modems the 'storage
index' is a property which is not available in all types of images (e.g. 'PRI'
images don't have it).
Therefore, instead of using a unique 'slot' identifier we'll just use the
'name' of the firmware as unique ID.
Also, currently skip the handling of 'available' images, and the method to
'Install()' new images, at least until we have one implementation defining what
to do with those.
