Don't account for Tempo in specialized endgames

The evaluation is already done by the specialized
function, don't need to add something elese later.

With this patch following positions are evaluated
correctly as draws:

8/6p1/1Pkp1p1p/2nNn2P/2P1K1P1/8/8/3B4 w - - 7
8/1k4p1/1P1p1p1p/3NnK1P/2P3P1/1n6/4B3/8 w - -

Verified it not regress with an STC test:
LLR: 3.15 (-2.94,2.94) [-3.00,1.00]
Total: 49812 W: 10095 L: 10016 D: 29701

Reported by Arjun Temurnikar.

bench: 8289983

src/evaluate.cpp

@@ -702,7 +702,7 @@ namespace {
     // If we have a specialized evaluation function for the current material
     // configuration, call it and return.
     if (ei.mi->specialized_eval_exists())
-        return ei.mi->evaluate(pos) + Eval::Tempo;
+        return ei.mi->evaluate(pos);
 
     // Probe the pawn hash table
     ei.pi = Pawns::probe(pos, thisThread->pawnsTable);