Remove addition of 1ms to all timestamps

The +1 was a quick fix to avoid the division by zero, a more correct approach is to use 1ms as the minimum reported timestamp to avoid a division by zero.
Later timestamps no longer include an additional 1ms.

closes https://github.com/official-stockfish/Stockfish/pull/5778

No functional change

src/search.cpp

@@ -2117,7 +2117,7 @@ void SearchManager::pv(Search::Worker&           worker,
         if (!isExact)
             info.bound = bound;
 
-        TimePoint time = tm.elapsed_time() + 1;
+        TimePoint time = std::max(TimePoint(1), tm.elapsed_time());
         info.timeMs    = time;
         info.nodes     = nodes;
         info.nps       = nodes * 1000 / time;