PCI: rcar: Check platform_get_irq() return code

The current code does not check the return from platform_get_irq() so add
an error check and return if this call does fail.

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Simon Horman <horms+renesas@verge.net.au>
diff --git a/drivers/pci/host/pci-rcar-gen2.c b/drivers/pci/host/pci-rcar-gen2.c
index ceec147..201e4a4 100644
--- a/drivers/pci/host/pci-rcar-gen2.c
+++ b/drivers/pci/host/pci-rcar-gen2.c
@@ -308,6 +308,11 @@
 	priv->reg = reg;
 	priv->dev = &pdev->dev;
 
+	if (priv->irq < 0) {
+		dev_err(&pdev->dev, "no valid irq found\n");
+		return priv->irq;
+	}
+
 	return rcar_pci_add_controller(priv);
 }