Remove ancient support for kUnknown_SkColorType in SkBitmapDevice

Bug: skia:
Change-Id: I7559544f46b49be5ac6b38add8d1b61c010d3d6f
Reviewed-on: https://skia-review.googlesource.com/c/162284
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
1 file changed