Fix the issue that --limit is not working in --frame-parallel mode.

The reason is due to early break out before outputting all the frames inside
decoder.

Change-Id: I4a138fba08d12935c39bd7602c95f8c18b474e29

vpxdec.c

@@ -1080,9 +1080,6 @@ int main_loop(int argc, const char **argv_) {
         }
       }
     }
-
-    if (stop_after && frame_in >= stop_after)
-      break;
   }
 
   if (summary || progress) {