ACPI: VIOT: Do not dereference fwnode in struct device

In order to make the underneath API easier to change in the future,
prevent users from dereferencing fwnode from struct device.
Instead, use the specific dev_fwnode() and device_match_fwnode()
APIs for that.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/viot.c

@@ -88,7 +88,7 @@ static int __init viot_get_pci_iommu_fwnode(struct viot_iommu *viommu,
 		return -ENODEV;
 	}
 
-	fwnode = pdev->dev.fwnode;
+	fwnode = dev_fwnode(&pdev->dev);
 	if (!fwnode) {
 		/*
 		 * PCI devices aren't necessarily described by ACPI. Create a
@@ -101,7 +101,7 @@ static int __init viot_get_pci_iommu_fwnode(struct viot_iommu *viommu,
 		}
 		set_primary_fwnode(&pdev->dev, fwnode);
 	}
-	viommu->fwnode = pdev->dev.fwnode;
+	viommu->fwnode = dev_fwnode(&pdev->dev);
 	pci_dev_put(pdev);
 	return 0;
 }
@@ -314,7 +314,7 @@ static int viot_dev_iommu_init(struct device *dev, struct viot_iommu *viommu,
 		return -ENODEV;
 
 	/* We're not translating ourself */
-	if (viommu->fwnode == dev->fwnode)
+	if (device_match_fwnode(dev, viommu->fwnode))
 		return -EINVAL;
 
 	ops = iommu_ops_from_fwnode(viommu->fwnode);