xen: arm: move dom0 gic and timer device tree nodes under /xen-core-devices/
Julien observed that we were relying on the provided host DTB supplying
suitable #address-cells and #size-cells values to allow us to represent these
addresses, which may not reliably be the case. Moving these under our own
known (somewhat analogous to the use of /soc/ or /motherboard/ on some
platforms) allows us to control these sizes.
Since the new node is created out of thin air it does not have a corresponding
struct dt_device_node and therefore we cannot use dt_n_addr_cells or
dt_n_size_cells, we can use hardcoded constants instead. For the same reason
we define and use set_xen_range instead of dt_set_range.
The hypervisor, cpus and psci node all either defined #foo-cells for their
children or do not contain reg properties and therefore can remain at the top
level.
The logging in make_gic_node was inconsistent. Fix it.