Cloud Hypervisor put gaps back between boot and hotplug RAM
Brief
This is not the VFIO DMA mapping-gap crash already on the site.
Notes
Reinstate: c9d3187c2649. Device-area start: 778c94e7a332. Slot size check: 9737a0c59598. Fixes issue 8242. That matches an older layout they had removed.
Not a recast of e8dc35a7.
Commit c9d3187c2649f18b783ad6d6c9347e80a6d53c0f