PCI: xilinx: Create legacy IRQ domain with size 5

The driver expects to use hardware IRQ numbers 1 through 4 for INTX
interrupts, but only creates an IRQ domain of size 4 (ie. IRQ numbers 0
through 3). This results in a warning from irq_domain_associate when it
is called with hwirq=4:

     WARNING: CPU: 0 PID: 1 at kernel/irq/irqdomain.c:365
         irq_domain_associate+0x170/0x220
     error: hwirq 0x4 is too large for dummy
     Modules linked in:
     CPU: 0 PID: 1 Comm: swapper/0 Tainted: G        W
         4.12.0-rc5-00126-g19e1b3a10aad-dirty torvalds#427
     Stack : 0000000000000000 0000000000000004 0000000000000006 ffffffff8092c78a
             0000000000000061 ffffffff8018bf60 0000000000000000 0000000000000000
             ffffffff8088c287 ffffffff80811d18 a8000000ffc60000 ffffffff80926678
             0000000000000001 0000000000000000 ffffffff80887880 ffffffff80960000
             ffffffff80920000 ffffffff801e6744 ffffffff80887880 a8000000ffc4f8f8
             000000000000089c ffffffff8018d260 0000000000010000 ffffffff80811d18
             0000000000000000 0000000000000001 0000000000000000 0000000000000000
             0000000000000000 a8000000ffc4f840 0000000000000000 ffffffff8042cf34
             0000000000000000 0000000000000000 0000000000000000 0000000000040c00
             0000000000000000 ffffffff8010d1c8 0000000000000000 ffffffff8042cf34
             ...
     Call Trace:
     [<ffffffff8010d1c8>] show_stack+0x80/0xa0
     [<ffffffff8042cf34>] dump_stack+0xd4/0x110
     [<ffffffff8013ea98>] __warn+0xf0/0x108
     [<ffffffff8013eb14>] warn_slowpath_fmt+0x3c/0x48
     [<ffffffff80196528>] irq_domain_associate+0x170/0x220
     [<ffffffff80196bf0>] irq_create_mapping+0x88/0x118
     [<ffffffff801976a8>] irq_create_fwspec_mapping+0xb8/0x320
     [<ffffffff80197970>] irq_create_of_mapping+0x60/0x70
     [<ffffffff805d1318>] of_irq_parse_and_map_pci+0x20/0x38
     [<ffffffff8049c210>] pci_fixup_irqs+0x60/0xe0
     [<ffffffff8049cd64>] xilinx_pcie_probe+0x28c/0x478
     [<ffffffff804e8ca8>] platform_drv_probe+0x50/0xd0
     [<ffffffff804e73a4>] driver_probe_device+0x2c4/0x3a0
     [<ffffffff804e7544>] __driver_attach+0xc4/0xd0
     [<ffffffff804e5254>] bus_for_each_dev+0x64/0xa8
     [<ffffffff804e5e40>] bus_add_driver+0x1f0/0x268
     [<ffffffff804e8000>] driver_register+0x68/0x118
     [<ffffffff801001a4>] do_one_initcall+0x4c/0x178
     [<ffffffff808d3ca8>] kernel_init_freeable+0x204/0x2b0
     [<ffffffff80730b68>] kernel_init+0x10/0xf8
     [<ffffffff80106218>] ret_from_kernel_thread+0x14/0x1c

This patch avoids that warning by creating the legacy IRQ domain with
size 5 rather than 4, allowing it to cover the hwirq=4/INTD case.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: Bharat Kumar Gogada <bharatku@xilinx.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Michal Simek <michal.simek@xilinx.com>
Cc: Ravikiran Gummaluri <rgummal@xilinx.com>
Cc: linux-pci@vger.kernel.org

drivers/pci/host/pcie-xilinx.c

@@ -524,7 +524,7 @@ static int xilinx_pcie_init_irq_domain(struct xilinx_pcie_port *port)
 		return -ENODEV;
 	}
 
-	port->leg_domain = irq_domain_add_linear(pcie_intc_node, 4,
+	port->leg_domain = irq_domain_add_linear(pcie_intc_node, 1 + 4,
 						 &intx_domain_ops,
 						 port);
 	if (!port->leg_domain) {