Atlanta Hawks player DeAndre' Bembry was arrested early Friday morning -- after cops say they clocked him hitting 128 mph in a 55!!!!!!! Yeah, we asked the cops what he was driving -- a purple Dodge Charger. The Atlanta Police Dept. tells us ... cops were monitoring speed on the I-85 around 12:20 AM when Bembry's purple speed machine came blazing through ... so they tracked him down and pulled him over.