When Khalil Mack gets in his car Thursday and drives to the Napa Valley Marriott for the Raiders’ training camp, the defensive end is packing light. Rookie roommate Greg Townsend Jr. has been given the list of mandatory snacks. Most important, Mack’s not bringing any mental baggage, none of the accolades from last season or any of the expectations or hype for both him and the team this year. “I’m still learning, just trying to get better” Mack said, taking a break from his workout at San Francisco’s Empower Gym on Monday. Running back Latavius Murray now calls Mack “Slash,” after Mack became the first player in NFL history to earn first-team All-Pro honors at two positions in the same season (defensive end and outside linebacker). Mack, 25, finished with 15 sacks, one shy of the franchise record, and led all edge rushers in the NFL with 82 quarterback pressures and 54 run stops. The “Slash” nickname is also appropriate because Mack thinks he was two players last season, and the one wearing No.