PCI: altera: Fix error when INTx is 4

PCI interrupt lines start at 1, not at 0.  So, creates additional one
interrupt when register for irq domain.

Error when PCIe devices have 4 INTx:

  WARNING: CPU: 1 PID: 1 at kernel/irq/irqdomain.c:280
    irq_domain_associate+0x17c/0x1cc()
  error: hwirq 0x4 is too large for dummy

Tested on Ethernet adapter card with multi-functions.
Signed-off-by: Ley Foon Tan <lftan@altera.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/host/pcie-altera.c

@@ -467,7 +467,7 @@ static int altera_pcie_init_irq_domain(struct altera_pcie *pcie)
 	struct device_node *node = dev->of_node;
 
 	/* Setup INTx */
-	pcie->irq_domain = irq_domain_add_linear(node, INTX_NUM,
+	pcie->irq_domain = irq_domain_add_linear(node, INTX_NUM + 1,
 					&intx_domain_ops, pcie);
 	if (!pcie->irq_domain) {
 		dev_err(dev, "Failed to get a INTx IRQ domain\n");