ASoC: S3C: I2Sv2: Segregate hw_params callback

Towards having build for multiple SoCs segregate hw_params callback
for s3c2412 and s3c64xx.
Since, all new SoCs have s3c64xx like register map, we keep that as
default implementation if no SoC specific callback is already defined.

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>