Add our own version of linux/input.h

Avoids having to #define any values we're trying to use.

Header file is from Linux 3.15-rc8.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Jonas Ådahl <jadahl@gmail.com>
touchpad: break up a long line

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>