OvmfPkg: PciHostBridgeLib: set RootBus->NoExtendedConfigSpace

In "OvmfPkg/PciHostBridgeDxe/PciRootBridgeIo.c", the
RootBridgeIoCheckParameter() function hard-codes the maximum offset for
the PCI config space as 0xFF (see the MAX_PCI_REG_ADDRESS macro), which
matches OVMF's 0xCF8 / 0xCFC config access method.

The "MdeModulePkg/Bus/Pci/PciHostBridgeDxe" driver abstracts away config
space access via the PciSegmentLib class, so it has to be informed
separately about the config space size.

Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Marcel Apfelbaum <marcel@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>

OvmfPkg/Library/PciHostBridgeLib/PciHostBridgeLib.c

@@ -101,6 +101,8 @@ InitRootBridge (
   RootBus->Mem.Limit = PcdGet64 (PcdPciMmio32Base) +
                        (PcdGet64 (PcdPciMmio32Size) - 1);
 
+  RootBus->NoExtendedConfigSpace = TRUE;
+
   return EFI_OUT_OF_RESOURCES;
 }