ARM: sunxi: Introduce Allwinner A20 support

The Allwinner A20 is a dual-core Cortex-A7-based SoC. It is
pin-compatible with the A10, and re-uses most of the IPs found in it,
plus some additional ones like a Gigabit Ethernet controller.
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>

arch/arm/mach-sunxi/sunxi.c

@@ -134,6 +134,7 @@ static const char * const sunxi_board_dt_compat[] = {
 	"allwinner,sun5i-a10s",
 	"allwinner,sun5i-a13",
 	"allwinner,sun6i-a31",
+	"allwinner,sun7i-a20",
 	NULL,
 };