Remove av1_cost_bit()

It's more efficient to use av1_cost_literal() instead.

Change-Id: I50727d4a4ee06492b373c2e7831c224c5eae8735
diff --git a/av1/encoder/rd.h b/av1/encoder/rd.h
index 31057cd..44f2f1b 100644
--- a/av1/encoder/rd.h
+++ b/av1/encoder/rd.h
@@ -382,7 +382,7 @@
                                            int is_first,
                                            const int *head_cost_table,
                                            const int *tail_cost_table) {
-  if (eob_val == LAST_EOB) return av1_cost_zero(128);
+  if (eob_val == LAST_EOB) return av1_cost_literal(1);
   const int comb_symb = 2 * AOMMIN(token, TWO_TOKEN) - eob_val + is_first;
   int cost = head_cost_table[comb_symb];
   if (token > ONE_TOKEN) cost += tail_cost_table[token - TWO_TOKEN];