ASoC: S3C: I2Sv2: Unify clock source IDs

Rather than having the multiple definitions of the same clocks,
define them in one common place and refer by SoC specific names.

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