[POWERPC] Use global_number in ppc32 pci_controller

Make the pci_controller struct use global_number for the PHB domain number
instead of index to match what ppc64 does and reuse its pci_domain_nr code.

Introduced a pci-common.c to handle shared code between ppc32 & ppc64.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
diff --git a/include/asm-powerpc/pci-bridge.h b/include/asm-powerpc/pci-bridge.h
index e2b2b6b..80cfb4a 100644
--- a/include/asm-powerpc/pci-bridge.h
+++ b/include/asm-powerpc/pci-bridge.h
@@ -21,7 +21,6 @@
 struct pci_controller {
 	struct pci_bus *bus;
 	void *arch_data;
-	int index;			/* PCI domain number */
 	struct pci_controller *next;
 	struct device *parent;
 
@@ -60,6 +59,7 @@
 	 */
 	struct resource	io_resource;
 	struct resource mem_resources[3];
+	int global_number;		/* PCI domain number */
 };
 
 static inline struct pci_controller *pci_bus_to_host(struct pci_bus *bus)