Code implementing of_device_make_bus_id() in Barebox uses rather old
implementation from Linux kernel and has a very significan limitation
in that it will produce identical names for different DT nodes that
happen to have the same node name as well as "reg" property.

One such example, that tirggered this change, is "switch@0" nodes that
can be found in dts/src/arm/vf610-zii-dev-rev-c.dts

This commit replaces original code with the current Linux kernel
implementation that traverses DT hierarchy from leaf node to its root
concatenating node names in the process.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>