PCI: tegra: Use new OF interrupt mapping when possible

Use new OF interrupt mapping (of_irq_parse_and_map_pci()) when possible.
This is the recommended method of doing the IRQ mapping.  For old
devicetrees we fall back to the previous practice.

This allows interrupts to be remapped across bridges.

Tested-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
diff --git a/drivers/pci/host/pci-tegra.c b/drivers/pci/host/pci-tegra.c
index 330f7e3..083cf37 100644
--- a/drivers/pci/host/pci-tegra.c
+++ b/drivers/pci/host/pci-tegra.c
@@ -639,10 +639,15 @@
 static int tegra_pcie_map_irq(const struct pci_dev *pdev, u8 slot, u8 pin)
 {
 	struct tegra_pcie *pcie = sys_to_pcie(pdev->bus->sysdata);
+	int irq;
 
 	tegra_cpuidle_pcie_irqs_in_use();
 
-	return pcie->irq;
+	irq = of_irq_parse_and_map_pci(pdev, slot, pin);
+	if (!irq)
+		irq = pcie->irq;
+
+	return irq;
 }
 
 static void tegra_pcie_add_bus(struct pci_bus *bus)