platform/chrome: chromeos_laptop - rely on I2C to set up interrupt trigger

Instead of passing interrupt flags via platform data to drivers, or
hoping that drivers will do the right thing and set it up the way we
need, let's set up IRQ resource and attach it to the I2C board info, and
let I2C core set it up for us.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Benson Leung <bleung@chromium.org>