lavfi/avfilter: avoid a redundant av_opt_set_dict2() call

Current code first sets AVFilterContext-level options, then aplies the
leftover on the filter's private data. This is unnecessary, applying the
options to AVFilterContext with the AV_OPT_SEARCH_CHILDREN flag
accomplishes the same effect.

libavfilter/avfilter.c

@@ -887,7 +887,7 @@ int avfilter_init_dict(AVFilterContext *ctx, AVDictionary **options)
 {
     int ret = 0;
 
-    ret = av_opt_set_dict(ctx, options);
+    ret = av_opt_set_dict2(ctx, options, AV_OPT_SEARCH_CHILDREN);
     if (ret < 0) {
         av_log(ctx, AV_LOG_ERROR, "Error applying generic filter options.\n");
         return ret;
@@ -902,14 +902,6 @@ int avfilter_init_dict(AVFilterContext *ctx, AVDictionary **options)
         ctx->thread_type = 0;
     }
 
-    if (ctx->filter->priv_class) {
-        ret = av_opt_set_dict2(ctx->priv, options, AV_OPT_SEARCH_CHILDREN);
-        if (ret < 0) {
-            av_log(ctx, AV_LOG_ERROR, "Error applying options to the filter.\n");
-            return ret;
-        }
-    }
-
     if (ctx->filter->init)
         ret = ctx->filter->init(ctx);
     if (ret < 0)