Make sure to drop the reference taken to the iommu platform device when
looking up its driver data during of_xlate().

Fixes: 0df4fabe208d ("iommu/mediatek: Add mt8173 IOMMU driver")
Cc: stable@vger.kernel.org	# 4.6
Cc: Yong Wu <yong.wu@mediatek.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/iommu/mtk_iommu.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index 0e0285348d2b..8d8e85186188 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -974,6 +974,8 @@ static int mtk_iommu_of_xlate(struct device *dev,
 			return -EINVAL;
 
 		dev_iommu_priv_set(dev, platform_get_drvdata(m4updev));
+
+		put_device(&m4updev->dev);
 	}
 
 	return iommu_fwspec_add_ids(dev, args->args, 1);
-- 
2.49.1