wmavoice: Use proper size in memeset().

sizeof(array_functrion_argument) gives the size of the pointer type not
the size of the array to which it points.

libavcodec/wmavoice.c

@@ -315,7 +315,7 @@ static av_cold int decode_vbmtree(GetBitContext *gb, int8_t vbm_tree[25])
     };
     int cntr[8], n, res;
 
-    memset(vbm_tree, 0xff, sizeof(vbm_tree));
+    memset(vbm_tree, 0xff, sizeof(vbm_tree[0]) * 25);
     memset(cntr,     0,    sizeof(cntr));
     for (n = 0; n < 17; n++) {
         res = get_bits(gb, 3);