[PATCH] Fix ppc compile problem with gcc 3.4

There's an incorrect redefinition extern/static in prep_pci.

Just remove it.

arch/ppc/platforms/prep_pci.c

@@ -1171,8 +1171,6 @@ void __init
 prep_pcibios_fixup(void)
 {
         struct pci_dev *dev = NULL;
-        extern unsigned char *Motherboard_map;
-        extern unsigned char *Motherboard_routes;
 
 	prep_route_pci_interrupts();