Add Keyboard event support

There are some mouse/touchpad devices that are combined with a keyboard
into a single device. Since mice are now handled by CMT, we will have to
support those devices.
This code is modeled after keyboard handling in xf86-input-evdev.

BUG=chromium:367969
TEST=Plug in a Logitech K400r, then use the device. Keyboard and
touchpad should be working.

Change-Id: I510cbfd81f11d80bd87647edf588f68c1f7b08b3
Reviewed-on: https://chromium-review.googlesource.com/197370
Reviewed-by: Andrew de los Reyes <adlr@chromium.org>
Tested-by: Dennis Kempin <denniskempin@chromium.org>
Commit-Queue: Dennis Kempin <denniskempin@chromium.org>
3 files changed