Input: bcm5974 - Add support for the Macbook 5 (Unibody)

This patch adds support for the new unibody Macbook, with physically
integrated button and trackpad. Since the integrated button changes
the logic for touch-and-click, a device capability bit mask is now
reported in input_id.version, which can be picked up by user space
via a EVIOCGID call.

Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Tested-by: David M. Lary <dmlary@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>