ARM: dts: rockchip: add root compatible properties

Add the missing 'compatible' property to device tree root node of

 - rk3066a-bqcurie2.dts
 - rk3188-radxarock.dts

and document the new values.
Signed-off-by: Beniamino Galvani <b.galvani@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

Documentation/devicetree/bindings/arm/rockchip.txt

+Rockchip platforms device tree bindings
+---------------------------------------
+
+- bq Curie 2 tablet:
+    Required root node properties:
+      - compatible = "mundoreader,bq-curie2", "rockchip,rk3066a";
+
+- Radxa Rock board:
+    Required root node properties:
+      - compatible = "radxa,rock", "rockchip,rk3188";

arch/arm/boot/dts/rk3066a-bqcurie2.dts

@@ -18,6 +18,7 @@
 
 / {
 	model = "bq Curie 2";
+	compatible = "mundoreader,bq-curie2", "rockchip,rk3066a";
 
 	memory {
 		reg = <0x60000000 0x40000000>;

arch/arm/boot/dts/rk3188-radxarock.dts

@@ -17,6 +17,7 @@
 
 / {
 	model = "Radxa Rock";
+	compatible = "radxa,rock", "rockchip,rk3188";
 
 	memory {
 		reg = <0x60000000 0x80000000>;