pcm: always use codec->id instead of codec_id

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org

libavcodec/pcm.c

@@ -265,7 +265,7 @@ static int pcm_decode_frame(AVCodecContext *avctx, void *data,
 
     /* av_get_bits_per_sample returns 0 for AV_CODEC_ID_PCM_DVD */
     samples_per_block = 1;
-    if (AV_CODEC_ID_PCM_DVD == avctx->codec_id) {
+    if (avctx->codec->id == AV_CODEC_ID_PCM_DVD) {
         if (avctx->bits_per_coded_sample != 20 &&
             avctx->bits_per_coded_sample != 24) {
             av_log(avctx, AV_LOG_ERROR, "PCM DVD unsupported sample depth\n");