iommufd: Use iommu_paging_domain_alloc()

If the iommu driver doesn't implement its domain_alloc_user callback,
iommufd_hwpt_paging_alloc() rolls back to allocate an iommu paging domain.
Replace iommu_domain_alloc() with iommu_user_domain_alloc() to pass the
device pointer along the path.

Signed-off-by: Lu Baolu <[e-mail]>
Reviewed-by: Jason Gunthorpe <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Will Deacon <[e-mail]>

drivers/iommu/iommufd/hw_pagetable.c

···
 		}
 		hwpt->domain->owner = ops;
 	} else {
-		hwpt->domain = iommu_domain_alloc(idev->dev->bus);
-		if (!hwpt->domain) {
-			rc = -ENOMEM;
+		hwpt->domain = iommu_paging_domain_alloc(idev->dev);
+		if (IS_ERR(hwpt->domain)) {
+			rc = PTR_ERR(hwpt->domain);
+			hwpt->domain = NULL;
 			goto out_abort;
 		}
 	}