avcodec/internal: Bump sane_nb_chanels

This allows decoding more als reference samples
Suggested-by: Thilo Borgmann <thilo.borgmann@mail.de>
Reviewed-by: Thilo Borgmann <thilo.borgmann@mail.de>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/internal.h

@@ -83,7 +83,7 @@
 #define FF_QSCALE_TYPE_H264  2
 #define FF_QSCALE_TYPE_VP56  3
 
-#define FF_SANE_NB_CHANNELS 256U
+#define FF_SANE_NB_CHANNELS 512U
 
 #define FF_SIGNBIT(x) ((x) >> CHAR_BIT * sizeof(x) - 1)