ARM: dts: bcm2711: Add firmware clocks node

Now that we have a clock driver for the clocks exposed by the firmware,
let's add the device tree nodes for it.

Tested-by: Nicolas Saenz Julienne <[e-mail]>
Signed-off-by: Maxime Ripard <[e-mail]>
Signed-off-by: Nicolas Saenz Julienne <[e-mail]>
Link: https://lore.kernel.org/r/9a6f1[e-mail]

arch/arm/boot/dts/bcm2711-rpi-4-b.dts

···
 };
 
 &firmware {
+	firmware_clocks: clocks {
+		compatible = "raspberrypi,firmware-clocks";
+		#clock-cells = <1>;
+	};
+
 	expgpio: gpio {
 		compatible = "raspberrypi,firmware-gpio";
 		gpio-controller;