[ALSA] ASoC AT91RM92000 audio DMA

This patch adds ASoC audio DMA support to the Atmel AT91RM9200 CPU.
Features:-
 o Playback/Capture supported.
 o 16 Bit data size.

Signed-off-by: Frank Mandarino <fmandarino@endrelia.com>
Signed-off-by: Liam Girdwood <liam.girdwood@wolfsonmicro.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>