This commit fixes two problems:
1) XTFI used to assemble the event itself, then passed it to the device. It's
much easier to just pass the variables into GPE/GKE and let the DIX do the
rest.
2) XTFI would pass the VCP/VCK as default device to event processing. As a
result, updating LEDs would be updated on the VCK, not on the actual keyboard.
Instead, we now pass the events through the last-used SD, thus toggling the
LEDs on the last keyboard that sent through this MD.
Also some cleanup in XTFI to merge validity checks a bit closer together
rather than having several different sections.
This breaks XTestFakeMotion with Xinerama though.
X.Org Bug 16145 <http://bugs.freedesktop.org/show_bug.cgi?id=16145>