avconv: Remove hw_device_ctx output filter reinit hack

Not needed any more because we no longer have any useful case which
will reinitialise with hardware frames here.

avconv_filter.c

@@ -317,7 +317,7 @@ static int configure_output_video_filter(FilterGraph *fg, OutputFilter *ofilter,
     if (ret < 0)
         return ret;
 
-    if (!hw_device_ctx && (ofilter->width || ofilter->height)) {
+    if (ofilter->width || ofilter->height) {
         char args[255];
         AVFilterContext *filter;