PCI: keystone: Make ks_dw_pcie_msi_domain_ops static

Make ks_dw_pcie_msi_domain_ops static because it is used only in this file.
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Murali Karicheri <m-karicheri2@ti.com>
Acked-by: Santosh Shilimkar<ssantosh@kernel.org>

drivers/pci/host/pci-keystone-dw.c

@@ -201,7 +201,7 @@ static int ks_dw_pcie_msi_map(struct irq_domain *domain, unsigned int irq,
 	return 0;
 }
 
-const struct irq_domain_ops ks_dw_pcie_msi_domain_ops = {
+static const struct irq_domain_ops ks_dw_pcie_msi_domain_ops = {
 	.map = ks_dw_pcie_msi_map,
 };