Reverse clamp logic in SkColorSpaceXform

Follow-up from https://skia-review.googlesource.com/c/10581/

Bug: skia:
Change-Id: I499f0908e1375854202c1cfd476827500fc89237
Reviewed-on: https://skia-review.googlesource.com/10645
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Mike Klein <mtklein@chromium.org>
1 file changed