Add missing x_device rules for XI2 functions, from Eamon Walsh.

Add missing x_device rules for XI2 functions, from Eamon Walsh.

> Whats the difference between add/remove and create/destroy?
>
> The devices are in a kind of hierarchy.  You can now create one or more
> "master devices" (mouse cursor and keyboard focus).  The physical input
> devices are "slave devices" that attach to master devices.
>
> Add/remove controls the ability to add/remove slave devices from a
> master device.  Create/destroy controls the ability to create new master
> devices.