ARM: dts: uniphier: rework UniPhier System Bus nodes

During the review process of the UniPhier System Bus driver
(drivers/bus/uniphier.c), the current binding of the System Bus
Controller turned out to be no good.  In order to make the driver
really usable, we have to switch over to the new binding defined by
Documentation/devicetree/bindings/bus/uniphier-system-bus.txt.
The old binding will be still supported for a while to keep the
backward compatibility.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>