iommu/vt-d: Move deferred device attachment into helper function

Move the code that does the deferred device attachment into a separate
helper function.

Fixes: 1ee0186b ("iommu/vt-d: Refactor find_domain() helper")
Cc: stable@vger.kernel.org # v5.5
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Acked-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/intel-iommu.c

@@ -2529,16 +2529,20 @@ struct dmar_domain *find_domain(struct device *dev)
 	return NULL;
 }
 
-static struct dmar_domain *deferred_attach_domain(struct device *dev)
+static void do_deferred_attach(struct device *dev)
 {
-	if (unlikely(attach_deferred(dev))) {
 	struct iommu_domain *domain;
 
 	dev->archdata.iommu = NULL;
 	domain = iommu_get_domain_for_dev(dev);
 	if (domain)
 		intel_iommu_attach_device(domain, dev);
-	}
+}
+
+static struct dmar_domain *deferred_attach_domain(struct device *dev)
+{
+	if (unlikely(attach_deferred(dev)))
+		do_deferred_attach(dev);
 
 	return find_domain(dev);
 }