Thunderbolt has a new kernel interface starting from version 4.13,
which simplifies updating the host controller and devices: the
kernel now exposes a sysfs interface for the non-volatile memory
as a device node. This can be used to write the new firmware blob.
Updates are then triggered also via a simple write to a sysfs
file (nvm_authenticate), which in turn is also used for error
reporting.
The plugin should be functionally, but a few items are missing:
- image verification
- safe mode handling
