sunxi: Add support for Tanix TX6

This commit adds support for Tanix TX6 TV box, based on H6. It's low end
H6 board, with 3 GiB of RAM, eMMC, fast ethernet, USB, IR and other
peripherals.

DT file is taken from Linux 5.11-rc1 release.

Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
diff --git a/board/sunxi/MAINTAINERS b/board/sunxi/MAINTAINERS
index 735801a..7a73a0b 100644
--- a/board/sunxi/MAINTAINERS
+++ b/board/sunxi/MAINTAINERS
@@ -494,6 +494,12 @@
 F:	configs/Sunchip_CX-A99_defconfig
 W:	https://linux-sunxi.org/Sunchip_CX-A99
 
+TANIX TX6 BOARD
+M:	Jernej Skrabec <jernej.skrabec@siol.net>
+S:	Maintained
+F:	configs/tanix_tx6_defconfig
+W:	https://linux-sunxi.org/Tanix_TX6
+
 TBS A711 BOARD
 M:	Maxime Ripard <mripard@kernel.org>
 S:	Maintained