Improve comment in SkICC.h

BUG=skia:

Change-Id: Ib0d30883a9e790bf1c4a85fce74a095a7df708c1
Reviewed-on: https://skia-review.googlesource.com/8908
Commit-Queue: Matt Sarett <msarett@google.com>
Reviewed-by: Mike Reed <reed@google.com>
1 file changed