Add `skcms_PixelFormat_GA_88` support for `skcms_Transform`.

Bug: chromium:40278281
Change-Id: I5dec2c12fe09ae0d66365e901100430cce5e9e2a
Reviewed-on: https://skia-review.googlesource.com/c/skcms/+/880812
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Ɓukasz Anforowicz <lukasza@google.com>
Reviewed-by: Leon Scroggins <scroggo@google.com>
6 files changed