ARM: dts: Make vcio a child of the firmware node

In order to resolve a potential startup order bug, the vcio driver has
been rewritten as a platform driver that depends on a DT node for
its instantiation and to locate the firmware driver.

Add that DT node.

See: #4620

Signed-off-by: Phil Elwell <[email protected]>

Author: pelwell

arch/arm/boot/dts/bcm270x-rpi.dtsi

@@ -152,3 +152,9 @@
 		status = "disabled";
 	};
 };
+
+&firmware {
+	vcio: vcio {
+		compatible = "raspberrypi,vcio";
+	};
+};