Since, through struct pci_host_bridge.map/swizzle_irq hooks, IRQs are now
allocated in the pci_assign_irq() callback automatically, PCI host bridge
drivers can stop relying on pci_fixup_irqs() for IRQ allocation.

Drop pci_fixup_irqs() usage from PCI iproc host bridge driver.
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Scott Branden <sbranden@broadcom.com>
Cc: Ray Jui <rjui@broadcom.com>
Cc: Jon Mason <jonmason@broadcom.com>