Riley Keough has paid tribute to her brother Benjamin after his death at the age of 27.The Logan Lucky star, 31, described her younger brother as “pure light” after he took his own life on Sunday.The siblings are the grandchildren of Elvis Presley and the children of his daughter Lisa Marie Presley.Sharing a string of photos of them together, Keough wrote: “Mornings are the hardest."I forget you’re gone. I can’t cry because of the fear that I will never stop.