You can't really 'fix' it per se, but depending on your budget, there are a few options. If you don't want to spend any money, and you don't really care how it looks as long it's black, just paint it black with well, anything. Permanent marker, acrylic paint, spray paint etc. If you're willing to spend a bit more then send it in to the workshop, but it won't be cheap, and i'm not sure whether they'll touch up such a small area. Overall it's up to you. If you value the guitar and think it's worth it, send it in. IMO a small paint chip won't really affect the tone, only how it looks.