ARM: dts: exynos: move assigned-clock* properties to i2s0 node in Odroid XU4

The purpose of those assigned-clock-* properties is to configure clock for
the I2S device so move them to respective node.  This silences the
dtschema warnings like:

  'clocks' is a dependency of 'assigned-clocks'

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20200906142146.21266-3-krzk@kernel.org