Preset min_tx_size in the encoder

Change-Id: I56c790821c1035e06d53392fbfee4fb4b7ed8b4d

av1/encoder/rdopt.c

@@ -4248,7 +4248,7 @@ static int64_t select_tx_size_fix_type(const AV1_COMP *cpi, MACROBLOCK *x,
 
   mbmi->tx_type = tx_type;
   inter_block_yrd(cpi, x, rd_stats, bsize, ref_best_rd, rd_stats_stack);
-  mbmi->min_tx_size = mbmi->inter_tx_size[0][0];
+  mbmi->min_tx_size = get_min_tx_size(mbmi->inter_tx_size[0][0]);
 
   if (rd_stats->rate == INT_MAX) return INT64_MAX;