Remove 8-bit array in HBD

Creating both 8- and 16-bit arrays and then only using one
of them is wasteful.

Change-Id: Ic5b397c283efaff7bcfff2d2413838ba3e065561

vp9/encoder/vp9_rdopt.c

@@ -2410,7 +2410,6 @@ static int64_t handle_inter_mode(VP9_COMP *cpi, MACROBLOCK *x,
   int_mv cur_mv[2];
 #if CONFIG_VP9_HIGHBITDEPTH
   DECLARE_ALIGNED_ARRAY(16, uint16_t, tmp_buf16, MAX_MB_PLANE * 64 * 64);
-  DECLARE_ALIGNED_ARRAY(16, uint8_t, tmp_buf8, MAX_MB_PLANE * 64 * 64);
   uint8_t *tmp_buf;
 #else
   DECLARE_ALIGNED_ARRAY(16, uint8_t, tmp_buf, MAX_MB_PLANE * 64 * 64);
@@ -2439,7 +2438,7 @@ static int64_t handle_inter_mode(VP9_COMP *cpi, MACROBLOCK *x,
   if (xd->cur_buf->flags & YV12_FLAG_HIGHBITDEPTH) {
     tmp_buf = CONVERT_TO_BYTEPTR(tmp_buf16);
   } else {
-    tmp_buf = tmp_buf8;
+    tmp_buf = (uint8_t *)tmp_buf16;
   }
 #endif  // CONFIG_VP9_HIGHBITDEPTH