Fix #1600

Removed unnecessary `` which cause problems with pgsql.
https://github.com/mybb/mybb/issues/1600
> It is inconsistent to the current code, you are being inconsistent with what has already coded. Why is is too difficult to keep the standards already defined in-code? Standard don't necessarily have to be documented.
There's nothing inconsistent here; both versions are used through the core. There're other coding things you should worry about (like the brackets placements) instead of things which are already different in different places.