ARM: dts: sun5i: Use sun5i-reference-design-tablet.dtsi for dit4350 dts

This results in quite a nice cleanup for this dts file.

Note as a side-effect this also enables the on board speaker / headphones
out. I've tested that this works as advertised.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>