avcodec/wmalosslessdec: use sizeof() instead of literal number

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/wmalosslessdec.c

@@ -652,10 +652,10 @@ static void mclms_update(WmallDecodeCtx *s, int icoef, int *pred)
     if (s->mclms_recent == 0) {
         memcpy(&s->mclms_prevvalues[order * num_channels],
                s->mclms_prevvalues,
-               2 * order * num_channels);
+               sizeof(int16_t) * order * num_channels);
         memcpy(&s->mclms_updates[order * num_channels],
                s->mclms_updates,
-               2 * order * num_channels);
+               sizeof(int16_t) * order * num_channels);
         s->mclms_recent = num_channels * order;
     }
 }