ATLANTA—A couple of clutch swings from breakout slugger Austin Riley got the underdog Atlanta Braves off to a fast start in the NL Championship Series. Riley homered and drove in the winning run with a single in the bottom of the ninth inning to give Atlanta a 3-2 victory over the Los Angeles Dodgers in Game 1 on Saturday night. Blake Treinen struck out Freddie Freeman to open the ninth before giving up Ozzie Albies’ bloop single to center field. Albies stole second and Riley followed with his line drive into the left-field corner. “That was my mindset—put something in play and see what happens,” Riley said after delivering the first walk-off hit of his career. The 24-year-old slugger spread his arms in celebration as he rounded first base before getting mobbed by teammates in a happy swarm that carried into shallow center field. “You dream of that as a …