iPhone 5S production has already kicked off, a Japanese-language Apple blog reported today. Foxconn has begun “partial production” of the iPhone 5S, a “reliable source” has told Macotakara. Both M acRumors and AppleInsider cited the report earlier today. The 5S is being built on the same production line as the iPhone 5, according to Macotakara The Japanese blog goes on to claim that NTT Docomo is cutting back on orders…