ARM: dts: bcm283x: Fix DTC warning for memory node

Compiling the bcm283x DTS with W=1 leads to the following warning:

Warning (unit_address_vs_reg): /memory: node has a reg or ranges property,
but no unit name

Fix this by adding the unit address.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Tested-by: Peter Robinson <pbrobinson@gmail.com>
Reviewed-by: Eric Anholt <eric@anholt.net>

arch/arm/boot/dts/bcm2836-rpi-2-b.dts

@@ -9,7 +9,7 @@
 	compatible = "raspberrypi,2-model-b", "brcm,bcm2836";
 	model = "Raspberry Pi 2 Model B";
 
-	memory {
+	memory@0 {
 		reg = <0 0x40000000>;
 	};