pci: let firmware reserve IO for pcie-pci-bridge

pci: let firmware reserve IO for pcie-pci-bridge

With [1] patch hotplug of rtl8139 succeeds, with caveat that it
fails to initialize IO bar, which is caused by [2] that makes
firmware skip IO reservation for any PCIe device, which isn't
correct in case of pcie-pci-bridge.
Fix it by exposing hotplug type and making IO resource optional
only if PCIe hotplug is in use.

[1]
 "pci: reserve resources for pcie-pci-bridge to fix regressed hotplug on q35"
[2]
Fixes: 76327b9f32a ("fw/pci: do not automatically allocate IO region for PCIe bridges")
Signed-off-by: Igor Mammedov imammedo@redhat.com
Tested-by: Laurent Vivier <lvivier@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
CC: mapfelba@redhat.com
CC: kraxel@redhat.com
CC: mst@redhat.com
CC: lvivier@redhat.com
CC: jusual@redhat.com