iommu/arm-smmu: Don't register fwnode for legacy binding

When using the legacy binding we bypass the of_xlate mechanism, so avoid
registering the instance fwnodes which act as keys for that. This will
help __iommu_probe_device() to retrieve the registered ops the same way
as for x86 etc. when no fwspec has previously been set up by of_xlate.

Acked-by: Will Deacon <will@kernel.org>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/18b0f812a42a74dd6924aea24e68ab409d6e1b52.1700589539.git.robin.murphy@arm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/arm/arm-smmu/arm-smmu.c

@@ -2161,7 +2161,8 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
 		return err;
 	}
 
-	err = iommu_device_register(&smmu->iommu, &arm_smmu_ops, dev);
+	err = iommu_device_register(&smmu->iommu, &arm_smmu_ops,
+				    using_legacy_binding ? NULL : dev);
 	if (err) {
 		dev_err(dev, "Failed to register iommu\n");
 		iommu_device_sysfs_remove(&smmu->iommu);