Change to initialize correct thread_data

BUG=aomedia:307

Change-Id: Ia1d39916b3e856acd33f4e199321395455151fb6

av1/encoder/ethread.c

diff --git a/av1/encoder/ethread.c b/av1/encoder/ethread.c
index 5dbafbb..1a60c84 100644
--- a/av1/encoder/ethread.c
+++ b/av1/encoder/ethread.c
@@ -89,7 +89,7 @@
 
         // Set up variance tree if needed.
         if (cpi->sf.partition_search_type == VAR_BASED_PARTITION)
-          av1_setup_var_tree(cm, &cpi->td);
+          av1_setup_var_tree(cm, thread_data->td);
 
         // Allocate frame counters in thread data.
         CHECK_MEM_ERROR(cm, thread_data->td->counts,