arm: sunxi: add support for V3s SoC

Allwinner V3s is a low-end single-core Cortex-A7 SoC, with 64MB
integrated DRAM, and several peripherals.

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

Documentation/arm/sunxi/README

@@ -71,6 +71,10 @@ SunXi family
         + Datasheet
           http://dl.linux-sunxi.org/H3/Allwinner_H3_Datasheet_V1.0.pdf
 
+      - Allwinner V3s (sun8i)
+        + Datasheet
+          http://linux-sunxi.org/File:Allwinner_V3s_Datasheet_V1.0.pdf
+
     * Quad ARM Cortex-A15, Quad ARM Cortex-A7 based SoCs
       - Allwinner A80
         + Datasheet