[idct] Fix initialization of tx_set_type

Previous assumption on reduced_tx_set_used=0 led to many assertion
failures and prevented signalling reduced_tx_set_used equal to 1.

BUG=aomedia:1053

Change-Id: If9a9dff8d01ba3ec942e06559c153f06d34555f9
diff --git a/av1/encoder/encodetxb.c b/av1/encoder/encodetxb.c
index 881f7b2..e0d25bd 100644
--- a/av1/encoder/encodetxb.c
+++ b/av1/encoder/encodetxb.c
@@ -2509,7 +2509,8 @@
                    a, l, 1);
 
     av1_inverse_transform_block_facade(xd, plane, block, blk_row, blk_col,
-                                       x->plane[plane].eobs[block]);
+                                       x->plane[plane].eobs[block],
+                                       cm->reduced_tx_set_used);
   }
   return best_rd;
 }