pci: introduce pci_swizzle_map_irq_fn() for standardized interrupt pin swizzle

pci: introduce pci_swizzle_map_irq_fn() for standardized interrupt pin swizzle

Introduce pci_swizzle_map_irq_fn() for interrupt pin swizzle which is
standardized. PCI bridge swizzle is common logic, by introducing
this function duplicated swizzle logic will be avoided later.

[[email protected]: drop opaque argument]
Reviewed-by: Paolo Bonzini <[email protected]>
Signed-off-by: Isaku Yamahata <[email protected]>
Signed-off-by: Jason Baron <[email protected]>
Signed-off-by: Michael S. Tsirkin <[email protected]>