dt-bindings: arm: Add Realtek RTD1295 bindings

The Zidoo X9S and a few other recent TV boxes feature the Realtek RTD1295,
a quad-core ARM Cortex-A53 SoC.
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Roc He <hepeng@zidoo.tv>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Andreas Färber <afaerber@suse.de>

Documentation/devicetree/bindings/arm/realtek.txt

+Realtek platforms device tree bindings
+--------------------------------------
+
+
+RTD1295 SoC
+===========
+
+Required root node properties:
+
+ - compatible :  must contain "realtek,rtd1295"
+
+
+Root node property compatible must contain, depending on board:
+
+ - Zidoo X9S: "zidoo,x9s"
+
+
+Example:
+
+    compatible = "zidoo,x9s", "realtek,rtd1295";