media: platform: mtk-mdp3: Fix return value check in mdp_probe()

In case of error, the function mtk_mutex_get()
returns ERR_PTR() and never returns NULL. The NULL test in the
return value check should be replaced with IS_ERR().
And also fix the err_free_mutex case.

Fixes: 61890cca ("media: platform: mtk-mdp3: add MediaTek MDP3 driver")
Signed-off-by: Qiheng Lin <linqiheng@huawei.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

drivers/media/platform/mediatek/mdp3/mtk-mdp3-core.c

@@ -207,8 +207,8 @@ static int mdp_probe(struct platform_device *pdev)
 	}
 	for (i = 0; i < MDP_PIPE_MAX; i++) {
 		mdp->mdp_mutex[i] = mtk_mutex_get(&mm_pdev->dev);
-		if (!mdp->mdp_mutex[i]) {
-			ret = -ENODEV;
+		if (IS_ERR(mdp->mdp_mutex[i])) {
+			ret = PTR_ERR(mdp->mdp_mutex[i]);
 			goto err_free_mutex;
 		}
 	}
@@ -289,7 +289,8 @@ static int mdp_probe(struct platform_device *pdev)
 	mdp_comp_destroy(mdp);
 err_free_mutex:
 	for (i = 0; i < MDP_PIPE_MAX; i++)
-		mtk_mutex_put(mdp->mdp_mutex[i]);
+		if (!IS_ERR_OR_NULL(mdp->mdp_mutex[i]))
+			mtk_mutex_put(mdp->mdp_mutex[i]);
 err_destroy_device:
 	kfree(mdp);
 err_return: