ARM: dts: bcm283x: Add cells encoding format to firmware bus

With the introduction of 55c7c06 ("ARM: dts: bcm283x: Fix vc4's
firmware bus DMA limitations") the firmware bus has to comply with
/soc's DMA limitations. Ultimately linking both buses to a same
dma-ranges property. The patch (and author) missed the fact that a bus'
#address-cells and #size-cells properties are not inherited, but set to
a fixed value which, in this case, doesn't match /soc's. This, although
not breaking Linux's DMA mapping functionality, generates ugly dtc
warnings.

Fix the issue by adding the correct address and size cells properties
under the firmware bus.

Fixes: 55c7c06 ("ARM: dts: bcm283x: Fix vc4's firmware bus DMA limitations")
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Link: https://lore.kernel.org/r/20200326134413.12298-1-nsaenzjulienne@suse.de

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

@@ -14,6 +14,9 @@
 	soc {
 		firmware: firmware {
 			compatible = "raspberrypi,bcm2835-firmware", "simple-bus";
+			#address-cells = <1>;
+			#size-cells = <1>;
+
 			mboxes = <&mailbox>;
 			dma-ranges;
 		};