ARM: dt: tegra: sort nodes based on bus order

Sort the nodes according to the following rules:
* First, any overrides for properties or nodes created by included files,
  in the order they appeared in the include file.
* Second, any nodes with a reg property, in numerical order.
* Third, any nodes without a reg property, in alphabetical order of node
  name.

The second sorting rule at least will probably help if/when we need to
explicitly insert nodes for the various busses in Tegra; that will just
be an indentation change rather than also a node re-ordering.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Olof Johansson <olof@lixom.net>