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

[Patrick Georgi (Code Review)]

Attention is currently required from: Furquan Shaikh, Jamie Ryu, Wonkyu Kim, Ravishankar Sarawadi, Subrata Banik, Julius Werner, Nick Vaccaro, Raj Astekar, Srinidhi N Kaushik.
Patrick Georgi has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/58833 )

Change subject: src/lib: Support fallback option for fw_config
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Patch Set 7:

(2 comments)

Commit Message:

https://review.coreboot.org/c/coreboot/+/58833/comment/ecab93f9_3f80296e 
PS7, Line 7: 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.
Sorry, but this confuses readers more than it helps explain what's going on here.

How about:

src/lib/fw_config: Change fw_config sources priority

Request fw_config values from various sources (as enabled via Kconfig) until
a valid value has been read.

With this change, Chrome EC CBI takes precedence over CBFS fw_config.

File src/Kconfig:

https://review.coreboot.org/c/coreboot/+/58833/comment/65433007_bfae7c90 
PS7, Line 408: config FW_CONFIG_SOURCE_CBFS
Why move this?