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 <nsaenzjulienne@suse.de>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Link: https://lore.kernel.org/r/9a6f113140b3115150bfb18ecb248a48d58562cf.1592210452.git-series.maxime@cerno.tech

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

@@ -69,6 +69,11 @@ sd_vcc_reg: sd_vcc_reg {
 };
 
 &firmware {
+	firmware_clocks: clocks {
+		compatible = "raspberrypi,firmware-clocks";
+		#clock-cells = <1>;
+	};
+
 	expgpio: gpio {
 		compatible = "raspberrypi,firmware-gpio";
 		gpio-controller;