“KP sucks!’’ That was the calling card the sellout Garden crowd of 19,812 screamed at Porzingis, who was making his first return since his messy exit from the city that drafted him. This all started in 2017, when Porzingis blew off his exit interview with Phil Jackson. His exit would come with his trade to the Mavericks. During the national anthem, some voices screamed, “Traitor!’’ and much worse.