[S] Change in coreboot[main]: drivers/option: Add CBFS file based option backend

[Subrata Banik (Code Review)]

Attention is currently required from: Julius Werner, Nicholas Chin.

Subrata Banik has posted comments on this change by Nicholas Chin. ( https://review.coreboot.org/c/coreboot/+/85905?usp=email )

Change subject: drivers/option: Add CBFS file based option backend
......................................................................

Patch Set 4:

(1 comment)

Patchset:

PS4: 
you might need to make the below changes to allow option to be picked from soc/mainboard

```
 git diff 
diff --git a/src/Kconfig b/src/Kconfig
index 0a0643ebf6b..996971e9cf5 100644
--- a/src/Kconfig
+++ b/src/Kconfig
@@ -149,6 +149,7 @@ config UTIL_GENPARSER

choice
        prompt "Option backend to use"
+       default USE_CBFS_FILE_OPTION_BACKEND if HAVE_CBFS_FILE_OPTION_BACKEND
        default USE_MAINBOARD_SPECIFIC_OPTION_BACKEND if HAVE_MAINBOARD_SPECIFIC_OPTION_BACKEND
        default USE_OPTION_TABLE if NVRAMCUI_SECONDARY_PAYLOAD
        default USE_UEFI_VARIABLE_STORE if DRIVERS_EFI_VARIABLE_STORE && \
@@ -840,6 +841,15 @@ config NUM_THREADS
        help
          How many execution threads to cooperatively multitask with.

+config HAVE_CBFS_FILE_OPTION_BACKEND
+       bool
+       default n
+       help
+         Enable this option if your mainboard stores coreboot options
+         in files within the CBFS files. This option tells coreboot to
+         read option values from these files instead of using other
+         methods like embedded NVRAM.
+
 config HAVE_MAINBOARD_SPECIFIC_OPTION_BACKEND
        bool
        help
```