WASHINGTON, Feb 17 (Reuters) - Conservative radio talk show host Rush Limbaugh is expected to visit Afghanistan with the top U.S. aid official to spotlight America's aid work there, officials said on Thursday. Political commentator Mary Matalin, a former White House aide to Vice President Dick Cheney, will also be on the trip. She said she was not being paid to go and would pay her own way to Dubai but she believed the U.S. government would cover the cost of her visit to Afghanistan from there. The Bush administration has come under sharp criticism for the Education Department's...