iommu/ipmmu-vmsa: Clean up bus_set_iommu()

Stop calling bus_set_iommu() since it's now unnecessary. This also
leaves the custom initcall effectively doing nothing but register
the driver, which no longer needs to happen early either, so convert
it to builtin_platform_driver().
Signed-off-by: NRobin Murphy <robin.murphy@arm.com>
Reported-by: Nkernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/r/14377566e449950c19367f75ec1b09724bf0889f.1660572783.git.robin.murphy@arm.comSigned-off-by: NJoerg Roedel <jroedel@suse.de>

drivers/iommu/ipmmu-vmsa.c

@@ -1090,11 +1090,6 @@ static int ipmmu_probe(struct platform_device *pdev)
 		ret = iommu_device_register(&mmu->iommu, &ipmmu_ops, &pdev->dev);
 		if (ret)
 			return ret;
-
-#if defined(CONFIG_IOMMU_DMA)
-		if (!iommu_present(&platform_bus_type))
-			bus_set_iommu(&platform_bus_type, &ipmmu_ops);
-#endif
 	}
 
 	/*
@@ -1168,32 +1163,4 @@ static struct platform_driver ipmmu_driver = {
 	.probe = ipmmu_probe,
 	.remove	= ipmmu_remove,
 };
-
-static int __init ipmmu_init(void)
-{
-	struct device_node *np;
-	static bool setup_done;
-	int ret;
-
-	if (setup_done)
-		return 0;
-
-	np = of_find_matching_node(NULL, ipmmu_of_ids);
-	if (!np)
-		return 0;
-
-	of_node_put(np);
-
-	ret = platform_driver_register(&ipmmu_driver);
-	if (ret < 0)
-		return ret;
-
-#if defined(CONFIG_ARM) && !defined(CONFIG_IOMMU_DMA)
-	if (!iommu_present(&platform_bus_type))
-		bus_set_iommu(&platform_bus_type, &ipmmu_ops);
-#endif
-
-	setup_done = true;
-	return 0;
-}
-subsys_initcall(ipmmu_init);
+builtin_platform_driver(ipmmu_driver);