sunxi: add orangepi zero defconfig

Orange Pi Zero is a board designed by Xunlong. It has an Allwinner H2+
SoC (similar to H3, which shares the same SoC ID), 256MB/512MB RAM,
Allwinner XR819 SDIO Wi-Fi, a MicroUSB port which is used to power the
board (also capable of OTG), a USB Type-A socket and a MicroSD slot.

Signed-off-by: Icenowy Zheng <icenowy@aosc.xyz>
Reviewed-by: Jagan Teki <jagan@openedev.com>
diff --git a/board/sunxi/MAINTAINERS b/board/sunxi/MAINTAINERS
index e23d45e..2321b8b 100644
--- a/board/sunxi/MAINTAINERS
+++ b/board/sunxi/MAINTAINERS
@@ -237,6 +237,11 @@
 S:	Maintained
 F:	configs/Nintendo_NES_Classic_Edition_defconfig
 
+ORANGEPI ZERO BOARD
+M:	Icenowy Zheng <icenowy@aosc.xyz>
+S:	Maintained
+F:	configs/orangepi_zero_defconfig
+
 R16 EVB PARROT BOARD
 M:	Quentin Schulz <quentin.schulz@free-electrons.com>
 S:	Maintained