ASoC: Samsung: Rename DMA device

Some Samsung SoCs have a PCM(DSP) controller. So the name
s3c24xx-pcm-audio for DMA driver is not very appropraite.
This patch moves :-
	s3c24xx-pcm-audio -> samsung-audio

Signed-off-by: Jassi Brar <jassi.brar@samsung.com>
Acked-by: Kukjin Kim <kgene.kim@samsung.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>