Input: ALPS - move v7 packet info to Documentation and v6 packet info

This patch move all packet info from driver source code to documentation
and adds info about v6 packet format (from driver source code).

Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>