v4l2videoenc: fix capture-io-mode property get

https://bugzilla.gnome.org/show_bug.cgi?id=791841
diff --git a/sys/v4l2/gstv4l2videoenc.c b/sys/v4l2/gstv4l2videoenc.c
index 4a1a8af..5f2daaf 100644
--- a/sys/v4l2/gstv4l2videoenc.c
+++ b/sys/v4l2/gstv4l2videoenc.c
@@ -95,8 +95,8 @@
           prop_id, value, pspec);
       break;
     case PROP_CAPTURE_IO_MODE:
-      gst_v4l2_object_get_property_helper (self->v4l2output,
-          PROP_IO_MODE, value, pspec);
+      gst_v4l2_object_get_property_helper (self->v4l2capture,
+          prop_id, value, pspec);
       break;
 
       /* By default read from output */