ASoC: fix au1x platform

This patch fixes up the au1x audio platform after the multi-component
merge:
- compile fixes and updates to get DB1200 platform audio working again,
- removal of global variables in AC97/I2S/DMA(PCM) modules.

The AC97 part is limited to one instance only for now due to issues
with getting at driver data in the soc_ac97_ops.

Signed-off-by: Manuel Lauss <manuel.lauss@googlemail.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>