Refactor skip_intra_in_interframe feature

Refactored skip_intra_in_interframe, and removed
the threshold feature related to skip_intra_in_interframe.

Change-Id: I42378714d609c209959b2db153d0421887605c4c
diff --git a/av1/encoder/rdopt.c b/av1/encoder/rdopt.c
index 0cfadc8..d6f3f79 100644
--- a/av1/encoder/rdopt.c
+++ b/av1/encoder/rdopt.c
@@ -5544,8 +5544,9 @@
 #endif
   // Gate intra mode evaluation if best of inter is skip except when source
   // variance is extremely low
+  const unsigned int src_var_thresh_intra_skip = 1;
   if (sf->intra_sf.skip_intra_in_interframe &&
-      (x->source_variance > sf->intra_sf.src_var_thresh_intra_skip)) {
+      (x->source_variance > src_var_thresh_intra_skip)) {
     if (inter_cost >= 0 && intra_cost >= 0) {
       aom_clear_system_state();
       const NN_CONFIG *nn_config = (AOMMIN(cm->width, cm->height) <= 480)
diff --git a/av1/encoder/speed_features.c b/av1/encoder/speed_features.c
index 206ac52..81b58c9 100644
--- a/av1/encoder/speed_features.c
+++ b/av1/encoder/speed_features.c
@@ -1188,7 +1188,6 @@
   intra_sf->chroma_intra_pruning_with_hog = 0;
   intra_sf->skip_intra_in_interframe = 1;
   intra_sf->intra_pruning_with_hog = 0;
-  intra_sf->src_var_thresh_intra_skip = 1;
   intra_sf->prune_palette_search_level = 0;
 
   for (int i = 0; i < TX_SIZES; i++) {
diff --git a/av1/encoder/speed_features.h b/av1/encoder/speed_features.h
index da522b7..4c60c28 100644
--- a/av1/encoder/speed_features.h
+++ b/av1/encoder/speed_features.h
@@ -795,10 +795,6 @@
   // flag to allow skipping intra mode for inter frame prediction
   int skip_intra_in_interframe;
 
-  // variance threshold for intra mode gating when inter turned out to be skip
-  // in inter frame prediction
-  unsigned int src_var_thresh_intra_skip;
-
   // Prune intra mode candidates based on source block histogram of gradient.
   // Applies to luma plane only.
   int intra_pruning_with_hog;