Add tempo also to NNUE eval.

STC:
LLR: 2.93 (-2.94,2.94) {-0.50,1.50}
Total: 10608 W: 1507 L: 1358 D: 7743
Ptnml(0-2): 94, 945, 3074, 1100, 91
https://tests.stockfishchess.org/tests/view/5f2c5921b3ebe5cbfee85b8b

LTC:
LLR: 2.94 (-2.94,2.94) {0.25,1.75}
Total: 7536 W: 556 L: 448 D: 6532
Ptnml(0-2): 9, 383, 2881, 481, 14
https://tests.stockfishchess.org/tests/view/5f2c6f4461e3b6af64881e95

closes https://github.com/official-stockfish/Stockfish/pull/2919

Bench: 4746616

src/evaluate.cpp

@@ -947,7 +947,7 @@ Value Eval::evaluate(const Position& pos) {
       balance += 200 * (pos.count<PAWN>(WHITE) - pos.count<PAWN>(BLACK));
       // Take NNUE eval only on balanced positions
       if (abs(balance) < NNUEThreshold)
-         return NNUE::evaluate(pos);
+         return NNUE::evaluate(pos) + Tempo;
   }
   return Evaluation<NO_TRACE>(pos).value();
 }