PCI: rcar: 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.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Simon Horman <horms+renesas@verge.net.au>

drivers/pci/host/pci-rcar-gen2.c

@@ -15,6 +15,7 @@
 #include <linux/io.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/of_pci.h>
 #include <linux/pci.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
@@ -180,8 +181,13 @@ static int rcar_pci_map_irq(const struct pci_dev *dev, u8 slot, u8 pin)
 {
 	struct pci_sys_data *sys = dev->bus->sysdata;
 	struct rcar_pci_priv *priv = sys->private_data;
+	int irq;
 
-	return priv->irq;
+	irq = of_irq_parse_and_map_pci(dev, slot, pin);
+	if (!irq)
+		irq = priv->irq;
+
+	return irq;
 }
 
 #ifdef CONFIG_PCI_DEBUG