Extcon: Arizona: Add driver for Wolfson Arizona class devices

Most Wolfson Arizona class audio hub CODECs include a flexible ultra low
power accessory detection subsystem. This driver exposes initial support
for this subsystem via the Extcon framework, implementing support for
ultra low power detection of headphone and headset with the ability to
detect the polarity of a headset.

The functionality of the devices is much richer and more flexible than
the current driver, future patches will extend the features of the
driver to more fully exploit this.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>