Add consts in set_fixed_partitioning()

Change-Id: Ib8c1b3b0a5a5689d3261dc822a69e9d473b89be1

vp9/encoder/vp9_encodeframe.c

@@ -1320,8 +1320,8 @@ static void set_fixed_partitioning(VP9_COMP *cpi, const TileInfo *const tile,
                                    BLOCK_SIZE bsize) {
   VP9_COMMON *const cm = &cpi->common;
   const int mis = cm->mi_stride;
-  int row8x8_remaining = tile->mi_row_end - mi_row;
-  int col8x8_remaining = tile->mi_col_end - mi_col;
+  const int row8x8_remaining = tile->mi_row_end - mi_row;
+  const int col8x8_remaining = tile->mi_col_end - mi_col;
   int block_row, block_col;
   MODE_INFO *mi_upper_left = cm->mi + mi_row * mis + mi_col;
   int bh = num_8x8_blocks_high_lookup[bsize];