iommu/dart: Clean up bus_set_iommu()

Stop calling bus_set_iommu() since it's now unnecessary, and simplify
the probe failure path accordingly.
Tested-by: Sven Peter <sven@svenpeter.dev>
Reviewed-by: Sven Peter <sven@svenpeter.dev>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/afe138964196907d58147a686c1dcd6a12f9e210.1660572783.git.robin.murphy@arm.comSigned-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/apple-dart.c

@@ -820,27 +820,6 @@ static irqreturn_t apple_dart_irq(int irq, void *dev)
 	return IRQ_HANDLED;
 }
 
-static int apple_dart_set_bus_ops(const struct iommu_ops *ops)
-{
-	int ret;
-
-	if (!iommu_present(&platform_bus_type)) {
-		ret = bus_set_iommu(&platform_bus_type, ops);
-		if (ret)
-			return ret;
-	}
-#ifdef CONFIG_PCI
-	if (!iommu_present(&pci_bus_type)) {
-		ret = bus_set_iommu(&pci_bus_type, ops);
-		if (ret) {
-			bus_set_iommu(&platform_bus_type, NULL);
-			return ret;
-		}
-	}
-#endif
-	return 0;
-}
-
 static int apple_dart_probe(struct platform_device *pdev)
 {
 	int ret;
@@ -895,14 +874,10 @@ static int apple_dart_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, dart);
 
-	ret = apple_dart_set_bus_ops(&apple_dart_iommu_ops);
-	if (ret)
-		goto err_free_irq;
-
 	ret = iommu_device_sysfs_add(&dart->iommu, dev, NULL, "apple-dart.%s",
 				     dev_name(&pdev->dev));
 	if (ret)
-		goto err_remove_bus_ops;
+		goto err_free_irq;
 
 	ret = iommu_device_register(&dart->iommu, &apple_dart_iommu_ops, dev);
 	if (ret)
@@ -916,8 +891,6 @@ static int apple_dart_probe(struct platform_device *pdev)
 
 err_sysfs_remove:
 	iommu_device_sysfs_remove(&dart->iommu);
-err_remove_bus_ops:
-	apple_dart_set_bus_ops(NULL);
 err_free_irq:
 	free_irq(dart->irq, dart);
 err_clk_disable:
@@ -932,7 +905,6 @@ static int apple_dart_remove(struct platform_device *pdev)
 
 	apple_dart_hw_reset(dart);
 	free_irq(dart->irq, dart);
-	apple_dart_set_bus_ops(NULL);
 
 	iommu_device_unregister(&dart->iommu);
 	iommu_device_sysfs_remove(&dart->iommu);