vexpress: Add virtio-mmio transports Add some virtio-mmio transports to the vexpress board model, together with a modify_dtb hook which adds them to the device tree so that the kernel will probe for them. We put them in a reserved area of the address map. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Message-id: 1373977512-28932-9-git-send-email-peter.maydell@linaro.org