PCI/MSI: xgene: Remove msi_controller assignment

After 8d63bc7beaee ("PCI/MSI: pci-xgene-msi: Get rid of struct
msi_controller"), it is no longer required to assign msi_controller for
X-Gene PCIe host bridge to support MSI.

Remove this unnecessary code. This also avoids a warning message ("failed
to enable MSI") during boot.

[bhelgaas: changelog]
Signed-off-by: Duc Dang <[e-mail]>
Signed-off-by: Bjorn Helgaas <[e-mail]>
Acked-by: Marc Zyngier <[e-mail]>
Cc: Tanmay Inamdar <[e-mail]>

drivers/pci/host/pci-xgene.c

···
 	return 0;
 }
 
-static int xgene_pcie_msi_enable(struct pci_bus *bus)
-{
-	struct device_node *msi_node;
-
-	msi_node = of_parse_phandle(bus->dev.of_node,
-					"msi-parent", 0);
-	if (!msi_node)
-		return -ENODEV;
-
-	bus->msi = of_pci_find_msi_chip_by_node(msi_node);
-	if (!bus->msi)
-		return -ENODEV;
-
-	of_node_put(msi_node);
-	bus->msi->dev = &bus->dev;
-	return 0;
-}
-
 static int xgene_pcie_probe_bridge(struct platform_device *pdev)
 {
 	struct device_node *dn = pdev->dev.of_node;
···
 					&xgene_pcie_ops, port, &res);
 	if (!bus)
 		return -ENOMEM;
-
-	if (IS_ENABLED(CONFIG_PCI_MSI))
-		if (xgene_pcie_msi_enable(bus))
-			dev_info(port->dev, "failed to enable MSI\n");
 
 	pci_scan_child_bus(bus);
 	pci_assign_unassigned_bus_resources(bus);