Input: wm97xx: add new AC97 bus support

This adds support for the new AC97 bus code, which discovers the devices
rather than uses platform data.

As part of this discovery, it enables a multi-function device wm97xx,
which supports touchscreen, battery, ADC and an audio codec. This patch
adds the code to bind the touchscreen "cell" as the touchscreen driver.

This was tested on the pxa architecture with a pxa270 + wm9713 + the
mioa701 touchscreen.

Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Acked-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>