drm/layerscape: fix handling fsl_dcu_drm_plane_index result

---
 drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_plane.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
 
diff --git a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_plane.c b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_plane.c
index 82be6b8..d1e300d 100644
--- a/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_plane.c
+++ b/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_plane.c
@@ -58,7 +58,8 @@ static void fsl_dcu_drm_plane_atomic_disable(struct drm_plane *plane,
 					     struct drm_plane_state *old_state)
 {
 	struct fsl_dcu_drm_device *fsl_dev = plane->dev->dev_private;
-	unsigned int index, value, ret;
+	unsigned int value;
+	int index, ret;
 
 	index = fsl_dcu_drm_plane_index(plane);
 	if (index < 0)