Fix bugs introduced in a previous patch

Introduced in I2c0bc4ba540886dd196e87a78b205407ad3e866b

Change-Id: I9ff49e7d37c5a1fea8dc8b5659a53697f76320df
diff --git a/av1/common/onyxc_int.h b/av1/common/onyxc_int.h
index 76db171..7e26a18 100644
--- a/av1/common/onyxc_int.h
+++ b/av1/common/onyxc_int.h
@@ -814,7 +814,7 @@
 
   if (max_tx_size >= TX_8X8) {
     category = (tx_size != max_tx_size && max_tx_size > TX_8X8) +
-               (TX_SIZES - 1 - tx_size) * 2;
+               (TX_SIZES - 1 - max_tx_size) * 2;
   }
   if (category == TXFM_PARTITION_CONTEXTS - 1) return category;
   return category * 3 + above + left;