Remove legacy SkSurface::MakeFromBackendRenderTarget that does not take SkColorType

Bug: skia:6718
Change-Id: Iefec5be49bf7450426c5ddb668f5525876f8ec2d
Reviewed-on: https://skia-review.googlesource.com/116194
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
5 files changed