This patch adds trackpad support for the MacBookAir4,1, released in July 2011.
It is very similar to the MacBookAir4,2 patch submitted by Joshua Dillon and
Chase Douglas.
Signed-off-by: Pieter-Augustijn Van Malleghem <p-a@scarlet.be>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>