Celtics guard Marcus Smart said he’s confident he’ll be back on the court for the postseason after undergoing thumb surgery last week. Smart suffered a complete tear of the ulnar collateral ligament in his right shooting hand while diving to the floor in a game against the Indiana Pacers earlier this month. A hand specialist in New York advised immediate surgery with hopes that Smart might be able to return even quicker than the six- to eight-week timeline the team announced after surgery. “I am confident [I’ll be back for the playoffs],” Smart said Monday night, his right arm completely wrapped, at his annual bowling fundraiser for his YounGameChanger Foundation. “I had one of the top [hand] doctors do it. The surgery was a success. Like she told me, you might as well go on and get it now. The quicker you can get it, the quicker the recovery.