PCI: spear13xx: Fix platform_get_irq() error handling

platform_get_irq() returns a negative number on failure, so adjust the
logic to detect such condition and propagate the real error value on
failure.

Signed-off-by: Fabio Estevam <[e-mail]>
Signed-off-by: Bjorn Helgaas <[e-mail]>
Cc: Pratyush Anand <[e-mail]>

drivers/pci/dwc/pcie-spear13xx.c

···
 	int ret;
 
 	pp->irq = platform_get_irq(pdev, 0);
-	if (!pp->irq) {
+	if (pp->irq < 0) {
 		dev_err(dev, "failed to get irq\n");
-		return -ENODEV;
+		return pp->irq;
 	}
 	ret = devm_request_irq(dev, pp->irq, spear13xx_pcie_irq_handler,
 			       IRQF_SHARED | IRQF_NO_THREAD,