input: bcm5974: Add support for MacBookAir3

This patch adds support for the MacBookAir3,1 and MacBookAir3,2
models.

[rydberg@euromail.se: touchpad range calibration]
Cc: stable@kernel.org
Signed-off-by: Edgar (gimli) Hucek <gimli@dark-green.com>
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>