By Se Young Lee SEOUL (Reuters) – Smartphone leader Samsung Electronics Co Ltd faces a third straight quarter of profit decline that could become a fourth as cheaper models grab a bigger share of a slowing market and Apple Inc readies the launch of its iPhone 6. Samsung Electronics’ woes, exacerbated by a won that has risen to a six-year high against the dollar, come at an awkward time for the flagship of South Korea’s largest conglomerate. The maker of the Galaxy smartphone is expected to say on Tuesday that earnings likely fell 12.6 percent for the quarter ended June, according to a Thomson Reuters I/B/E/S poll. “Samsung’s heyday has gone.