ASoC: Add Openmoko Neo FreeRunner (GTA02) audio driver

This driver supports the audio subsystem on the Openmoko Neo FreeRunner
smartphone, often known by its codename GTA02.  The system has a WM8753
connected to a Samsung S3C2442 with an external GPIO controlled speaker
amplifier.

The driver was originally written by Graeme Gregory and has recieved
contributions from Openmoko, myself and members of the Openmoko
community.  For much of this time the primary Openmoko kernel maintainer
was Andy Green.

Signed-off-by: Graeme Gregory <graeme@openmoko.com>
Signed-off-by: Andy Green <andy@openmoko.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>