[coreboot] build coreboot for Braswell soc

[philby john]

Hello,

My intention is to build coreboot for the Braswell soc. But looking at
src/Kconfig I realize none of the soc code (baytrail, braswell, broadwell)
can be compiled because the path to respective Kconfig soc's (source
"src/soc/*/*/Kconfig") have not been defined. Also the qa build environment
at qa.coreboot.org does not seem to build for Braswell.

Can someone please guide me on the procedure to compile the Braswell SoC
platform?

Thanks and regards,
Philby