This patch adds keyboard support for MacbookAir6,2 as WELLSPRING8
(0x0291, 0x0292, 0x0293). The touchpad is handled in a separate
bcm5974 patch, as usual.

Cc: stable@vger.kernel.org
Reported-and-tested-by: NBrad Ford <plymouthffl@gmail.com>
Signed-off-by: NHenrik Rydberg <rydberg@euromail.se>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>