ARM: s3c24xx: Drop unused struct s3c_audio_pdata entries

The s3c24xx-iis driver is now converted to use the dma_slave_map API
and the samsung-ac97 driver got removed from the tree so remove
the unused platform data structure instances.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>