ARM: sunxi: add support for R40 SoC

Allwinner R40 is a new SoC, with Quad Core Cortex-A7 and peripherals
like A20.

Add support for it.

Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
diff --git a/arch/arm/mach-sunxi/sunxi.c b/arch/arm/mach-sunxi/sunxi.c
index 7ab353f..5e9602c 100644
--- a/arch/arm/mach-sunxi/sunxi.c
+++ b/arch/arm/mach-sunxi/sunxi.c
@@ -65,6 +65,7 @@ static const char * const sun8i_board_dt_compat[] = {
 	"allwinner,sun8i-a83t",
 	"allwinner,sun8i-h2-plus",
 	"allwinner,sun8i-h3",
+	"allwinner,sun8i-r40",
 	"allwinner,sun8i-v3s",
 	NULL,
 };