arm: kirkwood: NSA310S: Add device tree DTS for Zyxel NSA310S board

Add device tree kirkwood-nsa310s.dts for Zyxel NSA310S board to
convert to Driver Model.

Signed-off-by: Tony Dinh <mibodhi@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/arch/arm/dts/Makefile b/arch/arm/dts/Makefile
index 90e3004..3941a08 100644
--- a/arch/arm/dts/Makefile
+++ b/arch/arm/dts/Makefile
@@ -56,6 +56,7 @@
 	kirkwood-ns2lite.dtb \
 	kirkwood-ns2max.dtb \
 	kirkwood-ns2mini.dtb \
+	kirkwood-nsa310s.dtb \
 	kirkwood-openrd-base.dtb \
 	kirkwood-openrd-client.dtb \
 	kirkwood-openrd-ultimate.dtb \