of, numa: Fetch empty NUMA node ID from distance map

There is no device node for the empty NUMA node. However, the
corresponding NUMA node ID and distance map is still valid in
"numa-distance-map-v1" compatible device node.

This fetches the NUMA node ID and distance map for these empty
NUMA node from "numa-distance-map-v1" compatible device node.

Signed-off-by: Gavin Shan <gshan@redhat.com>
Link: https://lore.kernel.org/r/20210927064119.127285-3-gshan@redhat.com


Signed-off-by: Rob Herring <robh@kernel.org>