drm/exynos: mixer: also allow NV21 for the video processor

All the necessary code is already there, just need to
handle the format in the switch statement.
Signed-off-by: NTobias Jakobi <tjakobi@math.uni-bielefeld.de>
Acked-by: NJoonyoung Shim <jy0922.shim@samsung.com>
Signed-off-by: NInki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/exynos_mixer.c

@@ -393,6 +393,9 @@ static void vp_video_buffer(struct mixer_context *ctx, int win)
 	case DRM_FORMAT_NV12:
 		crcb_mode = false;
 		break;
+	case DRM_FORMAT_NV21:
+		crcb_mode = true;
+		break;
 	default:
 		DRM_ERROR("pixel format for vp is wrong [%d].\n",
 				plane->pixel_format);