[coreboot-gerrit] [M] Change in coreboot[main]: commonlib/device_tree: Use enum cb_err instead of int

[Elyes Haouas (Code Review)]

Attention is currently required from: Elyes Haouas, Julius Werner.

Elyes Haouas has posted comments on this change by Elyes Haouas. ( https://review.coreboot.org/c/coreboot/+/84911?usp=email )

Change subject: commonlib/device_tree: Use enum cb_err instead of int
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