Requiring #ranges-address-cells and #ranges-size-cells

[mbolivar-nordic]

As of 4fc81d4, neither the
#ranges-address-cells nor #ranges-size-cells properties in the
"cpus,cluster" binding are required in the specification.

It doesn't seem possible to do much with a CPU cluster that doesn't
have this information, though, because there's no way to specify its
address map without them.

Shouldn't these be required?

[sstabellini]

Yes I think they should be required.