iommu/virtio: Clean up bus_set_iommu()

Stop calling bus_set_iommu() since it's now unnecessary, and simplify
the probe failure path accordingly.
Reviewed-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/0ff6f9166081724510e6772e43d45b317cab8c58.1660572783.git.robin.murphy@arm.comSigned-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/virtio-iommu.c

@@ -7,7 +7,6 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
-#include <linux/amba/bus.h>
 #include <linux/delay.h>
 #include <linux/dma-iommu.h>
 #include <linux/dma-map-ops.h>
@@ -17,7 +16,6 @@
 #include <linux/module.h>
 #include <linux/of_platform.h>
 #include <linux/pci.h>
-#include <linux/platform_device.h>
 #include <linux/virtio.h>
 #include <linux/virtio_config.h>
 #include <linux/virtio_ids.h>
@@ -1145,26 +1143,6 @@ static int viommu_probe(struct virtio_device *vdev)
 
 	iommu_device_register(&viommu->iommu, &viommu_ops, parent_dev);
 
-#ifdef CONFIG_PCI
-	if (pci_bus_type.iommu_ops != &viommu_ops) {
-		ret = bus_set_iommu(&pci_bus_type, &viommu_ops);
-		if (ret)
-			goto err_unregister;
-	}
-#endif
-#ifdef CONFIG_ARM_AMBA
-	if (amba_bustype.iommu_ops != &viommu_ops) {
-		ret = bus_set_iommu(&amba_bustype, &viommu_ops);
-		if (ret)
-			goto err_unregister;
-	}
-#endif
-	if (platform_bus_type.iommu_ops != &viommu_ops) {
-		ret = bus_set_iommu(&platform_bus_type, &viommu_ops);
-		if (ret)
-			goto err_unregister;
-	}
-
 	vdev->priv = viommu;
 
 	dev_info(dev, "input address: %u bits\n",
@@ -1173,9 +1151,6 @@ static int viommu_probe(struct virtio_device *vdev)
 
 	return 0;
 
-err_unregister:
-	iommu_device_sysfs_remove(&viommu->iommu);
-	iommu_device_unregister(&viommu->iommu);
 err_free_vqs:
 	vdev->config->del_vqs(vdev);