ASoC: Add initial support of Mitac mioa701 device SoC.

This machine driver enables sound functions on Mitac mio
a701 smartphone. Build upon ASoC v1, it handles :
 - rear speaker
 - front speaker
 - microphone
 - GSM

A global "Mio Mode" switch is not yet provided to cope with
audio path setup. As balance on audio chip line is no more
assured, an incorrect setup can produce a lot of heat and
even fry the battery behind the wm9713 and the speaker
amplifier.

It doesn't cope with :
 - headset jack
 - mio master mode
 - master volume control

This driver is backported from ASoc v2, and amputated from
scenario setups and master volume control.

[Minor mods for terminology in comments -- broonie]

Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>