Replace usage of SkTClamp with SkTPin

I prefer the SkTClamp spelling, but there were 4 uses vs. ~200. And
eventually we'll replace all of these with std::clamp anyway.

Change-Id: I418fce5080d089745c3f9eb42c36e3fc7962c895
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/269155
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
4 files changed