Change in coreboot[master]: device/Kconfig: Put gfx init methods into a `choice`

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Change subject: device/Kconfig: Put gfx init methods into a `choice`
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Patch Set 5: Verified+1

Build Successful

https://qa.coreboot.org/job/coreboot-checkpatch/10125/ : SUCCESS

https://qa.coreboot.org/job/coreboot-gerrit/54401/ : SUCCESS