fix wrong format set for GRAY16_BE

Because of a missing break, a wrong format will be set when trying
to use GRAY16_BE

Signed-off-by: Fabien Parent <fparent@baylibre.com>
diff --git a/sys/v4l2/gstv4l2object.c b/sys/v4l2/gstv4l2object.c
index 94ed123..4b4b29a 100644
--- a/sys/v4l2/gstv4l2object.c
+++ b/sys/v4l2/gstv4l2object.c
@@ -1848,6 +1848,7 @@
         break;
       case GST_VIDEO_FORMAT_GRAY16_BE:
         fourcc = V4L2_PIX_FMT_Y16_BE;
+        break;
       case GST_VIDEO_FORMAT_MT21:
         fourcc = V4L2_PIX_FMT_MT21;
 		break;