Check if tx_type is valid in av1_get_tx_type()

Change-Id: I717bcec45e061e9685c00282f1c2a4d53a3481ef
diff --git a/av1/common/blockd.h b/av1/common/blockd.h
index eeff0f2..384b59e 100644
--- a/av1/common/blockd.h
+++ b/av1/common/blockd.h
@@ -1035,8 +1035,7 @@
     }
   }
   assert(tx_type >= DCT_DCT && tx_type < TX_TYPES);
-  if (is_inter_block(mbmi) && !av1_ext_tx_used[tx_set_type][tx_type])
-    return DCT_DCT;
+  if (!av1_ext_tx_used[tx_set_type][tx_type]) return DCT_DCT;
   return tx_type;
 #endif  // CONFIG_TXK_SEL