ARM: dts: bcm2711: Add firmware usb reset node

Now that the reset driver exposing Raspberry Pi 4's firmware based USB
reset routine is available, let's add the device tree node exposing it.
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Link: https://lore.kernel.org/r/20200629161845.6021-4-nsaenzjulienne@suse.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

@@ -88,6 +88,11 @@ expgpio: gpio {
 				  "";
 		status = "okay";
 	};
+
+	reset: reset {
+		compatible = "raspberrypi,firmware-reset";
+		#reset-cells = <1>;
+	};
 };
 
 &gpio {