A 35-year-old North Andover man who is covered in “white power” tattoos will serve four to five years in prison for beating, berating and sexually abusing his stepdaughters, which prosecutors said was a racially motivated crime.Justin Ladd pleaded guilty yesterday to 32 counts of assault and battery with a dangerous weapon, indecent assault and battery, open and gross lewdness, and assaulting a person because of that person’s race.