remove references to kIndex_8_SkColorType from our tools/tests

Bug: skia:6828
Change-Id: Ib5049c28c11b7320bece20f5a0a886de8b2a4343
Reviewed-on: https://skia-review.googlesource.com/22728
Reviewed-by: Leon Scroggins <scroggo@google.com>
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Mike Reed <reed@google.com>
9 files changed