interlace: Send the reconfigure event in the right direction

Caught a warning (using fatal-warnings) setting the interlace's field-pattern:

#0  _g_log_abort (breakpoint=1) at ../../../glib/gmessages.c:554
#1  0x00007f002113a579 in g_logv (log_domain=0x7f00213553b0 <g_log_domain_gstreamer> "GStreamer", log_level=G_LOG_LEVEL_WARNING, format=<optimized out>, args=args@entry=0x7efeffffdce0) at ../../../glib/gmessages.c:1373
#2  0x00007f002113a743 in g_log (log_domain=<optimized out>, log_level=log_level@entry=G_LOG_LEVEL_WARNING, format=format@entry=0x7f00213688f0 "pad %s:%s pushing %s event in wrong direction") at ../../../glib/gmessages.c:1415
#3  0x00007f00212fae6a in gst_pad_push_event (pad=0x563675474c40, event=0x7efef8009800) at ../gst-build/subprojects/gstreamer/gst/gstpad.c:5646
#4  0x00007f0021226940 in object_set_property (nqueue=0x7f0014004bb0, value=0x7efeffffdee0, pspec=0x56367527e2d0, object=0x5636752982d0) at ../../../gobject/gobject.c:1565
#5  g_object_setv (values=<optimized out>, names=<optimized out>, n_properties=<optimized out>, object=0x5636752982d0) at ../../../gobject/gobject.c:2387
#6  g_object_setv (object=0x5636752982d0, n_properties=<optimized out>, names=<optimized out>, values=<optimized out>) at ../../../gobject/gobject.c:2361
#7  0x00007f002122788f in g_object_set_property (object=object@entry=0x5636752982d0, property_name=<optimized out>, value=value@entry=0x7efeffffdee0) at ../../../gobject/gobject.c:2678
#8  0x00007f002133259d in gst_util_set_object_arg (object=0x5636752982d0, name=<optimized out>, value=<optimized out>) at ../gst-build/subprojects/gstreamer/gst/gstutils.c:221
#9  0x0000563672f2dcb8 in <O as gstreamer::gobject::GObjectExtManualGst>::set_property_from_str (self=<optimized out>, name=..., value=...) at /builds/make.tv/app-videoengine/cargo/registry/src/github.com-1ecc6299db9ec823/gstreamer-0.16.7/src/gobject.rs:14

(The gst_interlace_set_property frame is missing because of a tail call to gst_pad_push_event.)