ATLANTA — Georgia hired Alabama defensive coordinator Kirby Smart as its new head coach on Sunday, hoping he can accomplish what been routine for the Crimson Tide but eluded Mark Richt during his 15 years between the hedges:Win a national championship. Smart was formally approved as Richt’s successor during a meeting by the Georgia athletic association executive committee. Several media outlets reported that Smart would be the choice just days after Georgia announced it was parting ways with Richt, who won two Southeastern Conference titles and nearly 75 percent of his games in Athens but fell out of favor with many top boosters because of a perception that his team’s underachieved.