[media] media: exynos4-is: fix deadlock on driver probe

Commit 0c426c4 ("[media] media: Always
keep a graph walk large enough around") changed
media_device_register_entity() function to take mdev->graph_mutex. This
causes deadlock in driver probe, which calls (indirectly) this function
with ->graph_mutex taken. This patch removes taking ->graph_mutex in
driver probe to avoid deadlock. Other drivers don't take ->graph_mutex
for entity registration, so this change should be safe.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Tested-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/platform/exynos4-is/media-dev.c

@@ -1446,22 +1446,13 @@ static int fimc_md_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, fmd);
 
-	/* Protect the media graph while we're registering entities */
-	mutex_lock(&fmd->media_dev.graph_mutex);
-
 	ret = fimc_md_register_platform_entities(fmd, dev->of_node);
-	if (ret) {
-		mutex_unlock(&fmd->media_dev.graph_mutex);
+	if (ret)
 		goto err_clk;
-	}
 
 	ret = fimc_md_register_sensor_entities(fmd);
-	if (ret) {
-		mutex_unlock(&fmd->media_dev.graph_mutex);
+	if (ret)
 		goto err_m_ent;
-	}
-
-	mutex_unlock(&fmd->media_dev.graph_mutex);
 
 	ret = device_create_file(&pdev->dev, &dev_attr_subdev_conf_mode);
 	if (ret)