* virtio memory mapped device

See http://ozlabs.org/~rusty/virtio-spec/ for more details.

Required properties:

- compatible:	"virtio,mmio" compatibility string
- reg:		control registers base address and size including configuration space
- interrupts:	interrupt generated by the device

Example:

	virtio_block@3000 {
		compatible = "virtio,mmio";
		reg = <0x3000 0x100>;
		interrupts = <41>;
	}
