ASoC: samsung: Odroid DT binding documentation corrections

This patch removes unused and undocumented samsung,cpu-dai,
samsung,codec-dai properties from the dts example and moves
sub-nodes' description to a separate section.

Suggested-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>