[ALSA] ASoC Samsung S3C24xx updates - i2s

This patch adds DMA size fields to the S3C24xx audio DMA params and
exports the S3C24xx I2S digital audio interface.

Signed-off-by: Graeme Gregory <gg@opensource.wolfsonmicro.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>