Fix build with --enable-internal-stats

Change-Id: I9649647cc5755c8411ddd56f92e7f96d421c2663
diff --git a/vp9/encoder/vp9_encodeframe.c b/vp9/encoder/vp9_encodeframe.c
index 12de8b7..13e4894 100644
--- a/vp9/encoder/vp9_encodeframe.c
+++ b/vp9/encoder/vp9_encodeframe.c
@@ -1104,7 +1104,7 @@
       THR_D63_PRED  /*D63_PRED*/,
       THR_TM        /*TM_PRED*/,
     };
-    ++cpi->mode_chosen_counts[kf_mode_index[mbmi->mode]];
+    ++cpi->mode_chosen_counts[kf_mode_index[mi->mode]];
   } else {
     // Note how often each mode chosen as best
     ++cpi->mode_chosen_counts[ctx->best_mode_index];