iommu: Make iommu_bus_notifier return NOTIFY_DONE rather than error code

In iommu_bus_notifier(), when action is
BUS_NOTIFY_ADD_DEVICE, it will return 'ops->add_device(dev)'
directly. But ops->add_device will return ERR_VAL, such as
-ENODEV. These value will make notifier_call_chain() not to
traverse the remain nodes in struct notifier_block list.

This patch revises iommu_bus_notifier() to return
NOTIFY_DONE when some errors happened in ops->add_device().

Signed-off-by: zhichang.yuan <yuanzhichang@hisilicon.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/iommu.c

@@ -1082,8 +1082,12 @@ static int iommu_bus_notifier(struct notifier_block *nb,
 	 * result in ADD/DEL notifiers to group->notifier
 	 */
 	if (action == BUS_NOTIFY_ADD_DEVICE) {
-		if (ops->add_device)
-			return ops->add_device(dev);
+		if (ops->add_device) {
+			int ret;
+
+			ret = ops->add_device(dev);
+			return (ret) ? NOTIFY_DONE : NOTIFY_OK;
+		}
 	} else if (action == BUS_NOTIFY_REMOVED_DEVICE) {
 		if (ops->remove_device && dev->iommu_group) {
 			ops->remove_device(dev);