Refactor ext-intra

Remove the code about block size dependent angle steps and deltas,
as they are modefied to be the same for all blocks in c81ea6e.

BUG=aomedia:442

Change-Id: I54607dd752ef895c1418f979410b14c02fc9ce22
diff --git a/av1/common/pred_common.c b/av1/common/pred_common.c
index afb27bf..f8041f8 100644
--- a/av1/common/pred_common.c
+++ b/av1/common/pred_common.c
@@ -108,7 +108,7 @@
   INTRA_FILTER ref_type = INTRA_FILTERS;
 
   if (ref_mbmi->sb_type >= BLOCK_8X8) {
-    PREDICTION_MODE mode = ref_mbmi->mode;
+    const PREDICTION_MODE mode = ref_mbmi->mode;
     if (is_inter_block(ref_mbmi)) {
 #if CONFIG_DUAL_FILTER
       switch (ref_mbmi->interp_filter[0]) {
@@ -123,9 +123,8 @@
       }
     } else {
       if (av1_is_directional_mode(mode, ref_mbmi->sb_type)) {
-        const int angle_step = av1_get_angle_step(ref_mbmi->sb_type, 0);
-        int p_angle =
-            mode_to_angle_map[mode] + ref_mbmi->angle_delta[0] * angle_step;
+        const int p_angle =
+            mode_to_angle_map[mode] + ref_mbmi->angle_delta[0] * ANGLE_STEP;
         if (av1_is_intra_filter_switchable(p_angle)) {
           ref_type = ref_mbmi->intra_filter;
         }