avfilter/vf_unsharp: Free out AVFrame on error

Fixes memleak
Fixes part of CID1197065

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavfilter/vf_unsharp.c

@@ -258,8 +258,10 @@ static int filter_frame(AVFilterLink *link, AVFrame *in)
 end:
     av_frame_free(&in);
 
-    if (ret < 0)
+    if (ret < 0) {
+        av_frame_free(&out);
         return ret;
+    }
     return ff_filter_frame(outlink, out);
 }