Fix a compiling error

BUG=aomedia:1702

Change-Id: I0471f7f789d207d0d47397c40c365cc80112d1a0

av1/encoder/rdopt.c

diff --git a/av1/encoder/rdopt.c b/av1/encoder/rdopt.c
index abfbe27..8bc1529 100644
--- a/av1/encoder/rdopt.c
+++ b/av1/encoder/rdopt.c
@@ -8308,7 +8308,7 @@
   const AV1_COMMON *const cm = &cpi->common;
   const SPEED_FEATURES *const sf = &cpi->sf;
   MACROBLOCKD *const xd = &x->e_mbd;
-  MB_MODE_INFO *const mbmi = &xd->mi[0]->mbmi;
+  MB_MODE_INFO *const mbmi = xd->mi[0];
   const int num_planes = av1_num_planes(cm);
 
   if (xd->lossless[mbmi->segment_id] == 0 && best_mode_index >= 0 &&