ARM: dove: SolidRun CuBox DT

This patch adds basic support for the SolidRun CuBox to DT based
mach-dove. There are still some issues related to ongoing orion/mvebu
development, e.g. gpio-led will not work as there is no DT pinctrl
for dove yet and we don't have board specific setup code. Nevertheless,
the DT description is already introduced here.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>