The White Sox might have said they’ve narrowed their choices for the first pick in the MLB Draft to three. But MLB Network is pretty confident there are really two. The network will have cameras with shortstops Roch Cholowsky of UCLA and Grady Emerson of Fort Worth (Texas) Christian High School to get either’s instant reaction when MLB commissioner Rob Manfred announces the pick Saturday in Philadelphia. Other prospects, such as catcher Vahn Lackey — whom the Sox included in their final three –