Devices may want to support more than one protocol, and for some devices
(e.g. Unifying peripherals stuck in bootloader mode) you might not even be able
to query for the correct protocol anyway.
The coreboot plugin never actually gained the ability to write. As it stands a
coreboot system now adds *two* system-firmware devices (from both flashrom and
coreboot) which isn't ideal.
Just allow flashrom to enumerate quirked devices and add coreboot-specific
metadata as required. If we require some kind of cbfs parsing then we can do
that in FuFlashromDevice->prepare_firmware().
