iommu/mediatek: Remove unnecessary check in attach_device

This priv_data is set in the of_xlate. if of_xlate failed, it should
not enter attach_device. remove the unnecessary check.
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Link: https://lore.kernel.org/r/20210111111914.22211-32-yong.wu@mediatek.comSigned-off-by: Will Deacon <will@kernel.org>

drivers/iommu/mtk_iommu.c

@@ -453,9 +453,6 @@ static int mtk_iommu_attach_device(struct iommu_domain *domain,
 	struct device *m4udev = data->dev;
 	int ret, domid;
 
-	if (!data)
-		return -ENODEV;
-
 	domid = mtk_iommu_get_domain_id(dev, data->plat_data);
 	if (domid < 0)
 		return domid;
@@ -492,9 +489,6 @@ static void mtk_iommu_detach_device(struct iommu_domain *domain,
 {
 	struct mtk_iommu_data *data = dev_iommu_priv_get(dev);
 
-	if (!data)
-		return;
-
 	mtk_iommu_config(data, dev, false, 0);
 }