A suspect was arrested Sunday on hate crime charges for yelling slurs at a 12-year-old boy in a Manhattan playground as he whipped the pre-teen victim with a belt, police said Sunday. Kevin Maxwell, 37, of Canarsie, Brooklyn, was charged with assault and menacing, both as hate crimes, and acting in a manner injurious to a child. Police say Maxwell confronted the victim outside the public bathroom at the Baruch Playground near Baruch Drive and E.