avfilter/vf_mergeplanes: Free inpads' names generically

Reviewed-by: Nicolas George <george@nsup.org>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavfilter/vf_mergeplanes.c

@@ -96,10 +96,8 @@ static av_cold int init(AVFilterContext *ctx)
         if (!pad.name)
             return AVERROR(ENOMEM);
 
-        if ((ret = ff_append_inpad(ctx, &pad)) < 0){
-            av_freep(&pad.name);
+        if ((ret = ff_append_inpad_free_name(ctx, &pad)) < 0)
             return ret;
-        }
     }
 
     return 0;
@@ -279,12 +277,8 @@ static int activate(AVFilterContext *ctx)
 static av_cold void uninit(AVFilterContext *ctx)
 {
     MergePlanesContext *s = ctx->priv;
-    int i;
 
     ff_framesync_uninit(&s->fs);
-
-    for (i = 0; i < ctx->nb_inputs; i++)
-        av_freep(&ctx->input_pads[i].name);
 }
 
 static const AVFilterPad mergeplanes_outputs[] = {