avfilter: simplify processing child context options

THe call to av_opt_set() is redundant, since the option is written in
the options dict, which is later passed to avfilter_init_dict().

libavfilter/avfilter.c

@@ -863,14 +863,11 @@ static int process_options(AVFilterContext *ctx, AVDictionary **options,
             }
         } else {
             av_dict_set(options, key, value, 0);
-            if ((ret = av_opt_set(ctx->priv, key, value, AV_OPT_SEARCH_CHILDREN)) < 0) {
-                if (!av_opt_find(ctx->priv, key, NULL, 0, AV_OPT_SEARCH_CHILDREN | AV_OPT_SEARCH_FAKE_OBJ)) {
-                    if (ret == AVERROR_OPTION_NOT_FOUND)
-                        av_log(ctx, AV_LOG_ERROR, "Option '%s' not found\n", key);
-                    av_free(value);
-                    av_free(parsed_key);
-                    return ret;
-                }
+            if (!av_opt_find(ctx->priv, key, NULL, 0, AV_OPT_SEARCH_CHILDREN | AV_OPT_SEARCH_FAKE_OBJ)) {
+                av_log(ctx, AV_LOG_ERROR, "Option '%s' not found\n", key);
+                av_free(value);
+                av_free(parsed_key);
+                return AVERROR_OPTION_NOT_FOUND;
             }
         }