Silient a compiler warning in av1_decode_block_tokens

Change-Id: I581bdb5edacd92fd40b28327fcd5bfb062dc9b5b

av1/decoder/detokenize.c

diff --git a/av1/decoder/detokenize.c b/av1/decoder/detokenize.c
index dffc56a..195b930 100644
--- a/av1/decoder/detokenize.c
+++ b/av1/decoder/detokenize.c
@@ -466,6 +466,8 @@
   if (xd->counts)
     av1_update_scan_count_facade(cm, xd->counts, tx_size, tx_type, pd->dqcoeff,
                                  eob);
+#else
+  (void)cm;
 #endif
   return eob;
 }