Remove many uses of kSkia8888 and kSkiaGamma8888

BUG=skia:

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=3405

Change-Id: Ie920f4bcbb3dd28114a66f2363643bb10009b840
Reviewed-on: https://skia-review.googlesource.com/3405
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
13 files changed