ASoC: samsung: Fix DTS breakage from missing dependencies

Revert "ARM: dts: Change i2s compatible string on exynos5250" (c7f7e6)
and "ARM: dts: exynos5250: move common i2s properties to exynos5 dtsi"
618728) since they reference DMA controller nodes that don't exist
causing DT build issues.

Reported-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Mark Brown <broonie@linaro.org>