v4l2videodec: Add resolution change support

Need free poll when object release.

https://bugzilla.gnome.org/show_bug.cgi?id=752962

UpStream Status: Pending
diff --git a/sys/v4l2/gstv4l2object.c b/sys/v4l2/gstv4l2object.c
index 13437b3..3ef8805 100644
--- a/sys/v4l2/gstv4l2object.c
+++ b/sys/v4l2/gstv4l2object.c
@@ -549,6 +549,8 @@
 {
   g_return_if_fail (v4l2object != NULL);
 
+  gst_poll_free (v4l2object->poll);
+
   g_free (v4l2object->videodev);
 
   g_free (v4l2object->channel);
@@ -4278,8 +4280,6 @@
     v4l2object->pool = NULL;
   }
 
-  gst_poll_free (v4l2object->poll);
-
   GST_V4L2_SET_INACTIVE (v4l2object);
 
 done: