There aren’t many Pittsburgh legends known with just one name. Say “Donnie” or, rather, “Dahnie,” in these parts and everyone knows exactly who you’re talking about.Donnie Iris has been a legend in Western Pennsylvania going all the way back to the late ‘60s as a member of The Jaggerz.Iris, whose soaring vocals powered the hits “Ah! Leah!,” “Love Is Like a Rock” and “My Girl,” died Monday, according to friends and bandmates, after battling bladder cancer for three years. He was 83. “For my money, he was the most beloved Pittsburgh musician of all time,” his colleague Joe Grushecky, said....