arm: sun8i: h3: drop skeleton.dtsi inclusion in H3 DTSI

The skeleton.dtsi file is now deprecated, and do not exist in ARM64
environment.

Since we will soon reuse most part of H3 DTSI for H5, which is an ARM64
chip, drop skeleton.dtsi inclusion now.

Signed-off-by: Icenowy Zheng <icenowy@aosc.xyz>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>