Input: bcm5974 - add support for the 2013 MacBook Air

commit 148c1c8ad3c4170186ebe6ea5900adde27d2a0e7 upstream.

The June 2013 Macbook Air (13'') has a new trackpad protocol; four new
values are inserted in the header, and the mode switch is no longer
needed. This patch adds support for the new devices.

Reported-and-tested-by: Brad Ford <plymouthffl@gmail.com>
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>