UK singer Rita Ora has landed a role in the highly anticipated movie adaptation of “Fifty Shades of Grey” — as character Christian Grey’s adopted sister, Mia. The movie based on the hit E.L. James S&M epic has finally begun to gel after the abrupt departure of male lead Charlie Hunnam (who was quickly replaced by Jamie Dornan to star opposite Dakota Johnson). Ora’s limited acting résumé includes a 2004 British film, “Spivs,” as well as cameos in “90210” and “Fast & Furious 6.”