Change in coreboot[master]: soc/intel/cannonlake: add uart.c to verstage

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Change subject: soc/intel/cannonlake: add uart.c to verstage
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Patch Set 3: Verified+1

Build Successful

https://qa.coreboot.org/job/coreboot-checkpatch/15159/ : SUCCESS

https://qa.coreboot.org/job/coreboot-gerrit/59904/ : SUCCESS