toshiba-acpi: Add support for Toshiba Illumination.

Add support for Toshiba Illumination. This is a set of LEDs installed on
some Toshiba laptops. It is controlled through ACPI, the commands has been
found through reverse engineering. It has been tested on a Toshiba Qosmio
G50-122.

Signed-off-by: Pierre Ducroquet <pinaraf@pinaraf.info>
Signed-off-by: Matthew Garrett <mjg@redhat.com>