iommu/omap: Increase group ref in .device_group()

Increase group refcounting in omap_iommu_device_group().
Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/omap-iommu.c

@@ -1536,7 +1536,7 @@ static struct iommu_group *omap_iommu_device_group(struct device *dev)
 	struct iommu_group *group = ERR_PTR(-EINVAL);
 
 	if (arch_data->iommu_dev)
-		group = arch_data->iommu_dev->group;
+		group = iommu_group_ref_get(arch_data->iommu_dev->group);
 
 	return group;
 }