x86/PCI: Refine PCI support check in pcibios_init()

Also consider raw_pci_ext_ops when validating if a system has PCI support.
This leads to proper resource allocation via pcibios_resource_survey() in
the case where PCI config space is exclusively accessed through MMCONFIG.

Signed-off-by: Adrian-Ken Rueegsegger <ken@codelabs.ch>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c
index 381a43c..8196054 100644
--- a/arch/x86/pci/common.c
+++ b/arch/x86/pci/common.c
@@ -516,7 +516,7 @@
 
 int __init pcibios_init(void)
 {
-	if (!raw_pci_ops) {
+	if (!raw_pci_ops && !raw_pci_ext_ops) {
 		printk(KERN_WARNING "PCI: System does not support PCI\n");
 		return 0;
 	}