FAYETTEVILLE, Ark. — Arkansas backup quarterback Malachi Singleton ran for an 11-yard touchdown with one minute, 17 seconds left in the fourth quarter and the Razorbacks stunned No. 4 Tennessee in a 19-14 upset Saturday night at Donald W. Reynolds Razorback Stadium. Nico Iamaleava completed a 42-yard pass to Dont’e Thornton on the game’s final possession, but the redshirt freshman quarterback ran out of bounds with no time left on the clock after getting flushed out of the pocked on fourth-and-5. Tennessee got the ball at its own 20-yard line with 4:05 left, clinging to a 14-13 lead, but the V…