Synchronize tx_size counts in the decoder

Make both encoder and decoder use depth index for frame count.

Change-Id: I96dddffc0a83ad5e4e2847b15391e01ba01ee502
diff --git a/av1/decoder/decodemv.c b/av1/decoder/decodemv.c
index 4ac6e32..31183c0 100644
--- a/av1/decoder/decodemv.c
+++ b/av1/decoder/decodemv.c
@@ -353,7 +353,7 @@
   int depth = aom_read_tree(r, av1_tx_size_tree[tx_size_cat],
                             cm->fc->tx_size_probs[tx_size_cat][ctx], ACCT_STR);
   TX_SIZE tx_size = depth_to_tx_size(depth);
-  if (counts) ++counts->tx_size[tx_size_cat][ctx][tx_size];
+  if (counts) ++counts->tx_size[tx_size_cat][ctx][depth];
   return tx_size;
 }