Change in coreboot[master]: src: Use NULL instead of 0 for pointer

[build bot (Jenkins) (Code Review)]

build bot (Jenkins) has posted comments on this change. ( https://review.coreboot.org/27096 )

Change subject: src: Use NULL instead of 0 for pointer
......................................................................

Patch Set 3: Verified-1

Build Unstable

https://qa.coreboot.org/job/coreboot-gerrit/74884/ : UNSTABLE

https://qa.coreboot.org/job/coreboot-checkpatch/28986/ : SUCCESS