sunxi: switch Allwinner A10 boards to OF_UPSTREAM

sunxi: switch Allwinner A10 boards to OF_UPSTREAM

In contrast to some other Allwinner SoCs, there is no difference between
the DTs for the Allwinner A10 SoCs (sun4i) between the U-Boot and the
Linux kernel repository.

Remove the old copies of the A10 related .dts and .dtsi files, and switch
most of sun4i boards over to use OF_UPSTREAM.

There are two boards for which we don't have DTs in the kernel tree.
Keep those two .dts files in the legacy U-Boot DT directory, and let
their defconfig opt out of OF_UPSTREAM.

Signed-off-by: Andre Przywara <[email protected]>
Acked-by: Sumit Garg <[email protected]>