x86, pci: Add arch_init to x86_init abstraction

Added an abstraction function for arch specific init calls.

Signed-off-by: Jacob Pan <[e-mail]>
Cc: Jesse Barnes <[e-mail]>
LKML-Reference: <[e-mail]>
Signed-off-by: H. Peter Anvin <[e-mail]>

arch/x86/include/asm/x86_init.h

···
 	int (*iommu_init)(void);
 };
 
- /*
-  * struct x86_init_pci - platform specific pci init functions
- * @init:			platform specific pci init
+/**
+ * struct x86_init_pci - platform specific pci init functions
+ * @arch_init:			platform specific pci arch init call
+ * @init:			platform specific pci subsystem init
  * @init_irq:			platform specific pci irq init
  * @fixup_irqs:			platform specific pci irq fixup
  */
 struct x86_init_pci {
+	int (*arch_init)(void);
 	int (*init)(void);
 	void (*init_irq)(void);
 	void (*fixup_irqs)(void);