Revert of use log2(scale) to compute mip level (patchset #7 id:120001 of https://codereview.chromium.org/849333002/)

Reason for revert:
need more suppressions

Original issue's description:
> use log2(scale) to compute mip level
>
> BUG=skia:
>
> Committed: https://skia.googlesource.com/skia/+/15fd47f8a07615a7f5d78581aee4c80ff9f17fd9

TBR=robertphillips@google.com,jvanverth@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Review URL: https://codereview.chromium.org/856783004