Sort subnodes of the soc node.
- The primary key is the bus address.
- The secondary key is the IP block.
- The tertiary key is the node name.

This is part of an ongoing effort to provide consistent node
order in the DT of Renesas SoCs to improve maintainability.

This should not have any run-time effect.
Signed-off-by: Yoshihiro Kaneko <ykaneko0929@gmail.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>