NVRAM, ChipCommon, etc).
This extends the existing handling of NVRAM core discovery to support
locating additional devices that may be attached either directly as real
cores, or indirectly via ChipCommon (e.g. bhnd_pmu).
When attached as a SoC root bus (as opposed to a bridged WiFi device),
the platform devices may not be attached until later bus passes,
necessitating delayed discovery/initialization.
Approved by: adrian (mentor)
Differential Revision: https://reviews.freebsd.org/D6962