sunxi: H616: switch to OF_UPSTREAM

sunxi: H616: switch to OF_UPSTREAM

With the recent "old-style sunxi" sync and the penultimate OF_UPSTREAM DT
update, both directories were based on the same v6.10 kernel tree.
And while there is one subtle difference in many Allwinner SoC's DT
files, the H616 ones turn out to be identical.

Remove the old copies of the H616 related .dts and .dtsi files, and
switch the whole H616 SoC over to use OF_UPSTREAM. This immediately
benefits from the recent upstream DT update, to kernel v6.11.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>