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>

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

@@ -308,6 +308,11 @@ static int __init rcar_pci_probe(struct platform_device *pdev)
 	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);
 }