PCI: arm: use generic pci_swizzle_interrupt_pin()

Use the generic pci_swizzle_interrupt_pin() instead of arch-specific code.

Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>