refine memory in av1_rd_pick_inter_mode_sb()

tmp_buf_orig in av1_rd_pick_inter_mode_sb() is allocated and freed repeatly,
and its usage is not overlapped with tmp_obmc_bufs, so use tmp_obmc_bufs[0] instead.

Change-Id: Ieb74cb58958cd69cd182fb9f8902b79a89564379
diff --git a/av1/encoder/ethread.c b/av1/encoder/ethread.c
index 13f5b8a..96afa36 100644
--- a/av1/encoder/ethread.c
+++ b/av1/encoder/ethread.c
@@ -416,7 +416,7 @@
       for (int j = 0; j < 2; ++j) {
         CHECK_MEM_ERROR(
             cm, thread_data->td->tmp_obmc_bufs[j],
-            aom_memalign(16, 2 * MAX_MB_PLANE * MAX_SB_SQUARE *
+            aom_memalign(32, 2 * MAX_MB_PLANE * MAX_SB_SQUARE *
                                  sizeof(*thread_data->td->tmp_obmc_bufs[j])));
       }
 
@@ -494,6 +494,7 @@
       thread_data->td->mb.above_pred_buf = thread_data->td->above_pred_buf;
       thread_data->td->mb.left_pred_buf = thread_data->td->left_pred_buf;
       thread_data->td->mb.wsrc_buf = thread_data->td->wsrc_buf;
+
 #if CONFIG_COLLECT_INTER_MODE_RD_STATS
       thread_data->td->mb.inter_modes_info = thread_data->td->inter_modes_info;
 #endif