More recent Lenovos like the T460s, T470s, T560s etc.
provide new hotkeys ids (LEN0268 instead of LEN0068)
and a newer version of the HKEY interface (0x200
instead of 0x100, as provided over the MHKV function).
This change allows detection and initialization of these
machines. It doesn't add support for the lenovo adaptive
keyboard, but allows this as a future change.
Tested on a T470s, some of the features work, e.g.
key events for most fn+Fx combinations over devd
and mute sound/detect mute. Other features
like lcd_brightness don't work, but are supported
over acpi_video anyway.
This also adds support for controlling the keyboard backlight found in newer lenovo models,
including support for the led(4) interface.