ffmpeg: Remove redundant null check

Fixes CID1396245
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

ffmpeg.c

@@ -3141,7 +3141,7 @@ static int init_output_stream_encode(OutputStream *ost)
                    ost->file_index, ost->index);
         }
 //      ost->frame_rate = ist->st->avg_frame_rate.num ? ist->st->avg_frame_rate : (AVRational){25, 1};
-        if (ost->enc && ost->enc->supported_framerates && !ost->force_fps) {
+        if (ost->enc->supported_framerates && !ost->force_fps) {
             int idx = av_find_nearest_q_idx(ost->frame_rate, ost->enc->supported_framerates);
             ost->frame_rate = ost->enc->supported_framerates[idx];
         }