Change in coreboot[master]: Makefile: Update clean targets

[build bot (Jenkins) (Code Review)]

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Change subject: Makefile: Update clean targets
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Patch Set 4: Verified-1

Build Failed

https://qa.coreboot.org/job/coreboot-gerrit/50878/ : FAILURE

https://qa.coreboot.org/job/coreboot-checkpatch/6853/ : SUCCESS