dt-bindings: Add root properties for Raspberry Pi 2

Signed-off-by: NEric Anholt <eric@anholt.net>
Acked-by: NRob Herring <robh@kernel.org>

Documentation/devicetree/bindings/arm/bcm/brcm,bcm2835.txt

@@ -26,6 +26,10 @@ Raspberry Pi Model B+
 Required root node properties:
 compatible = "raspberrypi,model-b-plus", "brcm,bcm2835";
 
+Raspberry Pi 2 Model B
+Required root node properties:
+compatible = "raspberrypi,2-model-b", "brcm,bcm2836";
+
 Raspberry Pi Compute Module
 Required root node properties:
 compatible = "raspberrypi,compute-module", "brcm,bcm2835";