Mysuru: Popularly known as ‘Rockstar’ among the South Indian film fraternity,  music composer  Devi Sri Prasad, famous as DSP, set the stage on fire on Day-4 of Yuva Dasara at the sprawling 100-acre land located on Uttanahalli Road in the city outskirts here yesterday. As soon as DSP entered the stage, audience whistled and cheered…