PCI: Add IRQ mapping function pointers to pci_host_bridge struct

In order to defer IRQ assignment arches must be able to register functions
to map and swizzle interrupts.  These registered functions are stored in
the pci_host_bridge struct.
Signed-off-by: Matthew Minter <matt@masarand.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

include/linux/pci.h

@@ -432,6 +432,8 @@ struct pci_host_bridge {
 	void *sysdata;
 	int busnr;
 	struct list_head windows;	/* resource_entry */
+	u8 (*swizzle_irq)(struct pci_dev *, u8 *); /* platform IRQ swizzler */
+	int (*map_irq)(const struct pci_dev *, u8, u8);
 	void (*release_fn)(struct pci_host_bridge *);
 	void *release_data;
 	struct msi_controller *msi;