Change in coreboot[master]: src/lib: add IS_ENABLED() around Kconfig symbol references

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Change subject: src/lib: add IS_ENABLED() around Kconfig symbol references
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Patch Set 1: Verified+1

Build Successful

https://qa.coreboot.org/job/coreboot-gerrit/56154/ : SUCCESS

https://qa.coreboot.org/job/coreboot-checkpatch/11757/ : SUCCESS