drm/exynos: checked for null pointer

Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>

drivers/gpu/drm/exynos/exynos_drm_encoder.c

@@ -283,6 +283,7 @@ void exynos_drm_encoder_crtc_mode_set(struct drm_encoder *encoder, void *data)
 	struct exynos_drm_overlay_ops *overlay_ops = manager->overlay_ops;
 	struct exynos_drm_overlay *overlay = data;
 
+	if (overlay_ops && overlay_ops->mode_set)
 		overlay_ops->mode_set(manager->dev, overlay);
 }
 
@@ -294,6 +295,7 @@ void exynos_drm_encoder_crtc_disable(struct drm_encoder *encoder, void *data)
 
 	DRM_DEBUG_KMS("\n");
 
+	if (overlay_ops && overlay_ops->disable)
 		overlay_ops->disable(manager->dev);
 
 	/*