Remove the unused enum ScaleFactor

closes https://github.com/official-stockfish/Stockfish/pull/4740

No functional change

AUTHORS

@@ -74,6 +74,7 @@ fanon
 Fauzi Akram Dabat (FauziAkram)
 Felix Wittmann
 gamander
+Gabriele Lombardo (gabe)
 Gary Heckman (gheckman)
 George Sobala (gsobala)
 gguliash

src/types.h

@@ -157,13 +157,6 @@ enum Phase {
   MG = 0, EG = 1, PHASE_NB = 2
 };
 
-enum ScaleFactor {
-  SCALE_FACTOR_DRAW    = 0,
-  SCALE_FACTOR_NORMAL  = 64,
-  SCALE_FACTOR_MAX     = 128,
-  SCALE_FACTOR_NONE    = 255
-};
-
 enum Bound {
   BOUND_NONE,
   BOUND_UPPER,