arm64: Include NUMA locality info in the CPU topology

The scheduler uses this topology to try and preserve locality when
migrating threads between CPUs and when performing work stealing.
Ensure that on NUMA systems it will at least take the NUMA topology into
account.

Reviewed by: mmel
Submitted by: Klara, Inc.
Sponsored by: Ampere Computing
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D28579