ARM: dts: bcm283x: Correct mailbox register sizes

The size field in a Device Tree "reg" property is encoded in bytes, not
words.

Fixes: 614fa221 ("ARM: dts: bcm2835: Add VCHIQ node to the Raspberry Pi boards. (v3)")
Signed-off-by: Phil Elwell <phil@raspberrypi.org>
Acked-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>

arch/arm/boot/dts/bcm2835-rpi.dtsi

@@ -32,7 +32,7 @@ power: power {
 
 		vchiq: mailbox@7e00b840 {
 			compatible = "brcm,bcm2835-vchiq";
-			reg = <0x7e00b840 0xf>;
+			reg = <0x7e00b840 0x3c>;
 			interrupts = <0 2>;
 		};
 	};