Thank you for notifying us with the data. Appreciated.
I did some stuff with BYT-I and BYT-M. I would expect, if you run FSP on BYT-I Stepping D0, to see for CPUID 0x30679, and for MCU to see 0x901, 0x903 and maybe more. If you run BYT-M Stepping C0, to see for CPUID 0x30678 and MCU 0x322, 0x324 or 0x325 (if I recall correctly).
If you see for BSW MCU 0x0, something is fishy. You do not have either any MCU to update with, or the new one (which you probably collected from the public site):
Intel® Pentium® and Celeron® Processor N3000 Product Families and Intel® Atom™ x5-Z8300 Processor (formerly Braswell, Compliant with FSP v1.1 Specification)...is somehow not reachable by Coreboot/Romstage.
So, I have here the following questions: