Raza Jaffrey, one of the stars of NBC’s Broadway backstager “Smash,” has lined up a West End gig, stepping into the role of Billy Flynn in “Chicago” in May.Jaffrey’s stage credits include the London productions of “Mamma Mia!” and “Bombay Dreams,” among others. His “Smash” character, a politico in the mayor’s office, doesn’t do much singing and dancing on the show, although Jaffrey performs in a Bollywood number in an upcoming seg airing in the U.S. April 23. The series began its run on SKY in the UK April 21. Jaffrey will join “Chicago” for about two months beginning in mid-May. His co-stars when he comes aboard will be Sarah Soetaert, Rachel McDowell and James Doherty.