ASoC: samsung: Remove unused Odroid x2/u3 machine driver

We have been using "simple-audio-card" for Odroid X2/U3 boards,
as can be seen from sound node in arch/arm/boot/dts/
exynos4412-odroid-common.dtsi. A dedicated machine driver is not
needed and it is removed in this patch.
There is no dts files using "samsung,odroidx2-audio" or
"samsung,odroidu3-audio" compatible strings.

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