ARM: S3C64XX: Added platform data header

Many SoCs have their I2S pins MUXed with other functions. So we need
to pass a callback for driver to configure the pins appropriately.
Hence, the need of platform data and this header.

As and when needed new callbacks and structure pointers maybe added to this
header.

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