PCI: hv: Fix return value check in hv_pci_assign_slots()

In case of error, the function pci_create_slot() returns ERR_PTR() and
never returns NULL. The NULL test in the return value check should be
replaced with IS_ERR().

Fixes: a15f2c08 ("PCI: hv: support reporting serial number as slot information")
Signed-off-by: NWei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/pci/controller/pci-hyperv.c

@@ -1484,8 +1484,10 @@ static void hv_pci_assign_slots(struct hv_pcibus_device *hbus)
 		snprintf(name, SLOT_NAME_SIZE, "%u", hpdev->desc.ser);
 		hpdev->pci_slot = pci_create_slot(hbus->pci_bus, slot_nr,
 					  name, NULL);
-		if (!hpdev->pci_slot)
+		if (IS_ERR(hpdev->pci_slot)) {
 			pr_warn("pci_create slot %s failed\n", name);
+			hpdev->pci_slot = NULL;
+		}
 	}
 }