avcodec/libopencore-amr: remove av_free coded_frame.

There seems to be nothing that sets coded_frame
also av_free is wrong
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/libopencore-amr.c

@@ -205,7 +205,6 @@ static av_cold int amr_nb_encode_init(AVCodecContext *avctx)
     s->enc_state = Encoder_Interface_init(s->enc_dtx);
     if (!s->enc_state) {
         av_log(avctx, AV_LOG_ERROR, "Encoder_Interface_init error\n");
-        av_freep(&avctx->coded_frame);
         return -1;
     }