We don't support any hardware that actually uses this proposed standard, and
nowadays there is much better public-key encryption people can easily use.
In many plugins we've wanted to use ->prepare_firmware() to parse the firmware
ahead of ->detach() and ->write_firmware() but this has the limitation that it
can only return a single blob of data.
For many devices, multiple binary blobs are required from one parsed image,
for instance providing signatures, config and data blobs that have to be pushed
to the device in different way.
This also means we parse the firmware *before* we ask the user to detach.
Break the internal FuDevice API to support these firmware types as they become
more popular.
This also allows us to move the Intel HEX and SREC parsing out of the dfu plugin
as they are used by a few plugins now, and resolving symbols between plugins
isn't exactly awesome.
The hardware does not support the DFU specification enough for a metadata table
to be embedded, so there's no way to reliably detect the 'devo' cipher, thus
making the support useless.
