Support rectangular tx_size in recursive txfm partition

This commit supports the recursive transform block partition to
start with both square and rectangular transform block sizes.

Change-Id: Idaf29d50cb1f4876b43e5ba82c2609708c6b1926
diff --git a/av1/encoder/encodemb.c b/av1/encoder/encodemb.c
index 8e873fe..d37654a 100644
--- a/av1/encoder/encodemb.c
+++ b/av1/encoder/encodemb.c
@@ -1182,7 +1182,7 @@
     const BLOCK_SIZE plane_bsize = get_plane_block_size(bsize, pd);
     const int mi_width = block_size_wide[plane_bsize] >> tx_size_wide_log2[0];
     const int mi_height = block_size_high[plane_bsize] >> tx_size_wide_log2[0];
-    const TX_SIZE max_tx_size = max_txsize_lookup[plane_bsize];
+    const TX_SIZE max_tx_size = max_txsize_rect_lookup[plane_bsize];
     const BLOCK_SIZE txb_size = txsize_to_bsize[max_tx_size];
     const int bw = block_size_wide[txb_size] >> tx_size_wide_log2[0];
     const int bh = block_size_high[txb_size] >> tx_size_wide_log2[0];