avformat/s337m: Use base AVClass for av_log usage

s337m_get_offset_and_codec does not make use of
AVFormatContext: AVClass is enough for logging.
Will facilitate further use from outside
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/s337m.c

@@ -31,7 +31,7 @@
 #define IS_24LE_MARKER(state)   ((state & 0xFFFFFFFFFFFF) == MARKER_24LE)
 #define IS_LE_MARKER(state)     (IS_16LE_MARKER(state) || IS_20LE_MARKER(state) || IS_24LE_MARKER(state))
 
-static int s337m_get_offset_and_codec(AVFormatContext *s,
+static int s337m_get_offset_and_codec(void *avc,
                                       uint64_t state,
                                       int data_type, int data_size,
                                       int *offset, enum AVCodecID *codec)
@@ -50,8 +50,8 @@ static int s337m_get_offset_and_codec(AVFormatContext *s,
     }
 
     if ((data_type & 0x1F) != 0x1C) {
-        if (s)
-            avpriv_report_missing_feature(s, "Data type %#x in SMPTE 337M", data_type & 0x1F);
+        if (avc)
+            avpriv_report_missing_feature(avc, "Data type %#x in SMPTE 337M", data_type & 0x1F);
         return AVERROR_PATCHWELCOME;
     }
 
@@ -72,8 +72,8 @@ static int s337m_get_offset_and_codec(AVFormatContext *s,
         *offset = 1601;
         break;
     default:
-        if (s)
-            avpriv_report_missing_feature(s, "Dolby E data size %d in SMPTE 337M", data_size);
+        if (avc)
+            avpriv_report_missing_feature(avc, "Dolby E data size %d in SMPTE 337M", data_size);
         return AVERROR_PATCHWELCOME;
     }