You’ll have to forgive Panthers linebacker Michael Barrett for looking ahead to a specific game. There’s still a chunk of time to get through, but the rookie has his eye on the second Sunday of the regular season. Panthers versus Chargers. Book it. The Sunday happens to be the day when Barrett, a former Michigan star, gets to meet up with his old coach, Jim Harbaugh. Since the Wolverines won the national championship back in January, Harbaugh decided to go back to the NFL, taking the head coaching job in LA. It could be a big maize and blue reunion. Barrett’s fellow linebacker and Michigan ex …