tpudrv12.h & targets/gtm900.h: our current support is for MGC2GSMT version only As it turns out, there exist two different Huawei-made hw platforms both bearing the marketing name GTM900-B: one is MG01GSMT, the other is MGC2GSMT. The two are NOT fw-compatible: aside from flash chip differences which should be handled by autodetection, the two hw platforms are already known to have different RFFEs with different control signals, and there may be other differences not yet known. Our current gtm900 build target is for MGC2GSMT only; we do not yet have a specimen of MG01GSMT on hand, hence no support for that version will be possible until and unless someone provides one.