(Bloomberg) — China plans to expand a ban on the use of iPhones in sensitive departments to government-backed agencies and state companies, a sign of growing challenges for Apple Inc. in its biggest foreign market and global production base. Most Read from Bloomberg Several agencies have begun instructing staff not to bring their iPhones to work, people familiar with the matter said, affirming a previous report from the Wall Street Journal. In addition, Beijing intends to extend that restriction far more broadly to a plethora of state-owned enterprises and other government-controlled organizations, the people said, asking not to be identified…