vapostproc: Update filters update_properties().

Right after instantiating the VA filter and changing the element
state, rebuild the image filters.

This will fix a regression from f20b3b815, where properties in a
gst-launch pipeline are not applied.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/2443>

sys/va/gstvavpp.c

@@ -398,6 +398,7 @@ gst_va_vpp_update_properties (GstVaBaseTransform * btrans)
 {
   GstVaVpp *self = GST_VA_VPP (btrans);
 
+  gst_va_vpp_rebuild_filters (self);
   _update_properties_unlocked (self);
 }