virtio: Bind virtio device to device-tree node

Bind the virtio devices with their of_node. This will help users of the
virtio devices to mention their dependencies on the device in the DT
itself. Like GPIO pin users can use the phandle of the device node, or
the node may contain more subnodes to add i2c or spi eeproms and other
users.

Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lore.kernel.org/r/94c12705602929968477aaf27e02439eb7a7f253.1627362340.git.viresh.kumar@linaro.org


Signed-off-by: Michael S. Tsirkin <mst@redhat.com>