pcihp: generate populated non-hotpluggble slot descriptions on non-hotplug path

Generating slots descriptions populated by non-hotpluggable devices
is akward at best and complicates hotplug path (build_append_pcihp_slots)
needlessly, and builds only dynamic _DSM for such slots which is overlkill.
Clean it up and let non-hotplug path (build_append_pci_bus_devices)
to handle that task.

Such clean up effectively drops dynamic _DSM methods on non-hotpluggable
slots (even though bus itself is hotpluggable), but in practice it
affects only built-in devices (ide controllers/various bridges) that don't
use acpi-index anyways so effectively it doesn't matter (NICs are hotpluggble).

Follow up series will add static _DSM for non-hotpluggble devices/buses
that will not depend on ACPI PCI hotplug at all, and potentially would
allows us to reuse non-hotplug path elsewhere (PBX/microvm/arm-virt),
including new support for acpi-index for non-hotpluggable devices.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <20230112140312.3096331-40-imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>