Raspberry Pi VideoCore firmware driver

Required properties:

- compatible:		Should be "raspberrypi,bcm2835-firmware"
- mboxes:		Phandle to the firmware device's Mailbox.
			  (See: ../mailbox/mailbox.txt for more information)

Example:

firmware {
	compatible = "raspberrypi,bcm2835-firmware";
	mboxes = <&mailbox>;
};