PXB does not work with unsupported bioses, but should
not interfere with normal OS operation.
We don't ship them anymore, but it's reasonable
to keep the work-around until we update the bios in qemu.

Fix this by not adding PXB mem/IO chunks to _CRS
if they weren't configured by BIOS.
Signed-off-by: NMarcel Apfelbaum <marcel@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Acked-by: NLaszlo Ersek <lersek@redhat.com>