It all depends on the specific area of entertainment law that you want to practice. There is no one general area that covers all of entertainment law, because entertainment law covers all aspects of the law. There are a lot of intellectual property, privacy and contract issues. However, there are also entertainment practices built around bankruptcy, government compliance, family, immigration, tax, probate and other legal areas.
Some schools might have a tailored pre-law or entertainment law program, so those classes would be good ones to take if they are available. However, if they are not available, then don't worry. There is no specified college course track for an entertainment lawyer. I would focus on any classes that emphasize reading and writing. Math, tax and accounting classes will be good too if you plan to have entertainment business clients.
If you want to increase your options and opportunities in the entertainment field, I suggest going to the best law school that you can get into, getting the best grades you can get, and then working for the best firm you can get hired at post-law school. For example, if you go Harvard Law (or some other tier 1 school) and work at a big firm right after law school, your options in the entertainment field will be virtually limitless. Everyone cannot get into Harvard, but if you can, then do it. If you can't, then go to the best rated school you can and get the best grades you can get. I didn't go to Harvard or work at a big firm, so it can be done, but you may have to take an alternate path to get into entertainment law.
In the meantime, work hard, live life to the fullest and meet as many people as you can meet. You should start networking with artists and musicians now, because today's unknown will be tomorrow's star. Networking will take you further than anything, and you will be in a good space in college to meet many young artists and musicians.