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

[Tim Wawrzynczak (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.
Tim Wawrzynczak 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 5:

(2 comments)

File src/lib/fw_config.c:

https://review.coreboot.org/c/coreboot/+/58833/comment/eec412bc_63e4d425 
PS5, Line 31: fw_config_value = UNDEFINED_FW_CONFIG;
this line is now redundant

https://review.coreboot.org/c/coreboot/+/58833/comment/2662c0a3_3478e397 
PS5, Line 43: fw_config_value = UNDEFINED_FW_CONFIG;
also redundant