Cleanup #306: Get rid of CBFS master header
Deal with walkcbfs_asm
To remove the CBFS master header, walkcbfs_asm needs to either be made aware of fmap or removed.
Current users (as determined by Arthur):
- Updating microcode before CAR on systems that don't do µcode updates through FIT
- Finding FSP-T on builds that use it (which is a bad idea anyway for root of trust concerns)