Switch HUION devices to tablet mode

Filing this here as a tracker bug. Right now we rely on huion-switcher for Huion devices to be switched to tablet mode. This requires reading the 0x409 language ID from the USB descriptor (amongst other things, see the huion-switcher or uclogic kernel driver sources).

The Huion Inspiroy 2 setup is difficult libwacom bug has an outline of the various bits that need to work together.

Ideally we'd have this in (or associated with) the BPF so all this is handled automatically.