PCI: aardvark: Move to struct pci_host_bridge IRQ mapping functions

struct pci_host_bridge gained hooks to map/swizzle IRQs, so that the IRQ
mapping can be done automatically by PCI core code through the
pci_assign_irq() function instead of resorting to arch-specific
implementation callbacks to carry out the same task which force PCI host
bridge drivers implementation to implement per-arch kludges to carry out a
task that is inherently architecture agnostic.

Commit 769b461f ("arm64: PCI: Drop DT IRQ allocation from
pcibios_alloc_irq()") was assuming all PCI host controller drivers had been
converted to use ->map_irq(), but that wasn't the case: pci-aardvark had
not been converted. Due to this, it broke the support for legacy PCI
interrupts when using the pci-aardvark driver (used on Marvell Armada 3720
platforms).

In order to fix this, we make sure the ->map_irq and ->swizzle_irq fields
of pci_host_bridge are properly filled in.

Fixes: 769b461f ("arm64: PCI: Drop DT IRQ allocation from pcibios_alloc_irq()")
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: stable@vger.kernel.org	# v4.13+