Change in coreboot[master]: soc/intel/common/opregion: Use enum cb_err as return value

[build bot (Jenkins) (Code Review)]

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Change subject: soc/intel/common/opregion: Use enum cb_err as return value
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Patch Set 2: Verified+1

Build Successful

https://qa.coreboot.org/job/coreboot-gerrit/56129/ : SUCCESS

https://qa.coreboot.org/job/coreboot-checkpatch/11733/ : SUCCESS