Add support for non-continuous MT21 format

In order to use non-continuous MT21 planes, we need to set correctly
its fourcc_nc.

Signed-off-by: Fabien Parent <fparent@baylibre.com>
diff --git a/sys/v4l2/gstv4l2object.c b/sys/v4l2/gstv4l2object.c
index 4b4b29a..8863727 100644
--- a/sys/v4l2/gstv4l2object.c
+++ b/sys/v4l2/gstv4l2object.c
@@ -1851,6 +1851,7 @@
         break;
       case GST_VIDEO_FORMAT_MT21:
         fourcc = V4L2_PIX_FMT_MT21;
+        fourcc_nc = V4L2_PIX_FMT_MT21;
 		break;
       default:
         break;