Prefer using get_tx_size()

Change-Id: Ifcdd3ce2953c1ecb1d0962da412a4b5ba2cda912
diff --git a/av1/encoder/rdopt.c b/av1/encoder/rdopt.c
index 9daa6c9..f721df0 100644
--- a/av1/encoder/rdopt.c
+++ b/av1/encoder/rdopt.c
@@ -1126,8 +1126,7 @@
 
 #if !CONFIG_VAR_TX && !CONFIG_SUPERTX
   // Check for consistency of tx_size with mode info
-  assert(type == PLANE_TYPE_Y ? mbmi->tx_size == tx_size
-                              : get_uv_tx_size(mbmi, pd) == tx_size);
+  assert(tx_size == get_tx_size(plane, xd));
 #endif  // !CONFIG_VAR_TX && !CONFIG_SUPERTX
   (void)cm;