dm: exynos: sound: Convert to use driver model

Update snow's device tree and config to use driver model for sound. Also
update the others as best we can.

Spring does not appear to have audio support in the kernel. The smdk5250
and smdk5420 boards use a wolfson codec which I cannot test with. So the
only boards that is tested and known to work are snow, pit and pi.

Signed-off-by: Simon Glass <sjg@chromium.org>