doc: add device enumeration and documentation

This adds some initial device enumeration for Wii and Wii U related
products. It also starts a thorough Wii-Remote communication specification
which will be expanded from time to time.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
doc: fix licensing information

Some parts of xwiimote are released under an MIT-like license. Other
parts are public-domain. MIT-like is basically 2-clause BSD but it might
confuse people so I removed the "BSD" references.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
driver: remove kernel driver copy

The driver is now part of upstream linux. No need to copy it into this
distribution.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>