Removed an incorrect assert() statement in search.cpp, which asserted that

Removed an incorrect assert() statement in search.cpp, which asserted that
a static eval cached in the transposition table would always equal the static
eval of the current position. This is in general not true, because the cached
value could be from a previous search with different evaluation parameter
settings, or from a search from the opposite side (Stockfish's evaluation
function is assymmetric by default).