NEW YORK — OG Anunoby’s only flustered moment came when Madison Square Garden chanted his name. After getting fouled following an offensive rebound midway through the second quarter of a blowout 112-84 Knicks victory over the Portland Trail Blazers on Tuesday, Anunoby stepped to the free throw line amid intensifying applause and relentless “OG” chants. His first free throw was off-target. Then he calmly sank the second. Anunoby scored 16 points on four-of-five shooting from downtown in the first quarter alone and finished the game with a team-high 23 points on 9-of-12 shooting from the field. …