Change in coreboot[master]: src/lib: Support fallback option for fw_config

[Wonkyu Kim (Code Review)]

Attention is currently required from: Wonkyu Kim.
Hello build bot (Jenkins),

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/coreboot/+/58833

to look at the new patch set (#2).

Change subject: src/lib: Support fallback option for fw_config
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src/lib: Support fallback option for fw_config

To support both non-chrome EC platform and chrome EC platform in
single coreboot binary, need to support fallback option.
Make reading fw_config from CBI and support other options as
fallback options and support backward compatiblity to support only one
option as before.

TEST=select both configs and check fallback behavior.
1. select both FW_CONFIG_SOURCE_CHROMEEC_CBI and FW_CONFIG_SOURCE_CBFS
2. check Coreboot tries to read CBI and CBFS

Signed-off-by: Wonkyu Kim 
Change-Id: I215c13a4fcb9dc3b94f73c770e704d4e353e9cff
---
M src/Kconfig
M src/lib/fw_config.c
2 files changed, 29 insertions(+), 27 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/33/58833/2