Remove unneeded no-op from motion_mode_rd

Change-Id: I083b74ee863afdf894e19a51741d7f4bb8c58f7f
diff --git a/av1/encoder/rdopt.c b/av1/encoder/rdopt.c
index 93bf8ea..1a6c42e 100644
--- a/av1/encoder/rdopt.c
+++ b/av1/encoder/rdopt.c
@@ -1389,7 +1389,6 @@
 
   assert(mbmi->ref_frame[1] != INTRA_FRAME);
   const MV_REFERENCE_FRAME ref_frame_1 = mbmi->ref_frame[1];
-  (void)tile_data;
   av1_invalid_rd_stats(&best_rd_stats);
   aom_clear_system_state();
   mbmi->num_proj_ref = 1;  // assume num_proj_ref >=1