LAS VEGAS — It will go down as another what if for Chael Sonnen. Sonnen stuck to his bread and butter in round one of his UFC 148 rematch with middleweight champion Anderson Silva on Saturday night, scoring an instant takedown and using his ground-and-pound to easily win the round. Then, in the second round, he went for a a spinning back elbow, a move rarely scene in his arsenal. He missed wildly, fell to the mat, and the champion pounced. Silva landed a huge, legal knee to the grounded Sonnen…