Simplify history bonus

After we recently added the disallowance for negative bonuses, it is no
longer necessary to keep the max comparison in the previous step.

Passed STC:
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 72000 W: 18820 L: 18637 D: 34543
Ptnml(0-2): 267, 8489, 18276, 8730, 238
https://tests.stockfishchess.org/tests/view/66ce132cbf8c9d8780fdabe7

Passed LTC:
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 67452 W: 17136 L: 16961 D: 33355
Ptnml(0-2): 35, 7489, 18519, 7632, 51
https://tests.stockfishchess.org/tests/view/66cf6ad49de3e7f9b33d1010

closes https://github.com/official-stockfish/Stockfish/pull/5554

Bench: 1147012

src/search.cpp

@@ -1347,7 +1347,7 @@ moves_loop:  // When in check, search starts here
                      + 134 * (!(ss - 1)->inCheck && bestValue <= -(ss - 1)->staticEval - 91));
 
         // Proportional to "how much damage we have to undo"
-        bonus += std::clamp(-(ss - 1)->statScore / 100, -94, 304);
+        bonus += std::min(-(ss - 1)->statScore / 100, 304);
 
         bonus = std::max(bonus, 0);