Change in coreboot[master]: commonlib/storage: Make sd_mmc_go_idle an api

[build bot (Jenkins) (Code Review)]

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Change subject: commonlib/storage: Make sd_mmc_go_idle an api
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Patch Set 3:

Build Successful

https://qa.coreboot.org/job/coreboot-checkpatch/23725/ : SUCCESS

https://qa.coreboot.org/job/coreboot-gerrit/69404/ : SUCCESS