[ALSA] soc - ASoC 0.13 AT91xxxx DMA

This patch updates the AT91xxxx audio DMA driver to the new API in ASoC
0.13.
Changes:-
o Updated to use new 0.13 data structures.
o Suspend and Resume now conditionally compiled.
o #include guard around at91-pcm.h header.

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