ARM: dts: s5p: Remove skeleton.dtsi inclusion for S5PV210

The skeleton.dtsi file was removed in ARM64 for different reasons as
explained in commit ("3ebee5a2 arm64: dts: kill skeleton.dtsi").

These also applies to ARM and it will also allow to get rid of the
following DTC warnings in the future:

"Node /memory has a reg or ranges property, but no unit name"

Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>