chess.php: fix Scrutinizer warning
chess.php: fix Scrutinizer warning

Fixes the warning:

> It seems like you are loosely comparing two booleans. Considering
> using the strict comparison === instead.

Instead, we just simplify the expression by omitting the unnecessary
comparison.

hemberger/smr,hemberger/smr,hemberger/smr,smrealms/smr,hemberger/smr,smrealms/smr,smrealms/smr