The Allwinner S3/S3L/V3 SoCs all share the same die with the V3s SoC,
but with more GPIO wired out of the package.

Add a DTSI file for these SoCs. It just replaces some compatible strings
of the V3s DTSI now. As these SoCs share the same feature set on Linux,
we use the first known chip (V3) as the file's name.
Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>