In preparation for cxl_acpi walking pci_root->bus->bridge, add that
association to the mock pci_root instances.
Note that the missing 3rd entry in mock_pci_root[] was not noticed until
now given that the test version of to_cxl_host_bridge()
(tools/testing/cxl/mock_acpi.c), obviated the need for that entry.
However, "cxl/acpi: Improve debug messages in cxl_acpi_probe()" [1]
needs pci_root->bus->bridge to be populated.
Link: https://lore.kernel.org/r/20221018132341.76259-6-rrichter@amd.com
Cc: Robert Richter <rrichter@amd.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
 
        return AE_OK;
 }
 
-static struct pci_bus mock_pci_bus[NR_CXL_HOST_BRIDGES];
-static struct acpi_pci_root mock_pci_root[NR_CXL_HOST_BRIDGES] = {
+static struct pci_bus mock_pci_bus[NR_CXL_HOST_BRIDGES + NR_CXL_SINGLE_HOST];
+static struct acpi_pci_root mock_pci_root[ARRAY_SIZE(mock_pci_bus)] = {
        [0] = {
                .bus = &mock_pci_bus[0],
        },
        [1] = {
                .bus = &mock_pci_bus[1],
        },
+       [2] = {
+               .bus = &mock_pci_bus[2],
+       },
+
 };
 
 static bool is_mock_bus(struct pci_bus *bus)
                }
 
                cxl_hb_single[i] = pdev;
+               mock_pci_bus[i + NR_CXL_HOST_BRIDGES].bridge = &pdev->dev;
                rc = sysfs_create_link(&pdev->dev.kobj, &pdev->dev.kobj,
                                       "physical_node");
                if (rc)
                }
 
                cxl_host_bridge[i] = pdev;
+               mock_pci_bus[i].bridge = &pdev->dev;
                rc = sysfs_create_link(&pdev->dev.kobj, &pdev->dev.kobj,
                                       "physical_node");
                if (rc)