remove the last vestiges of SkMScalar

Change-Id: I2a91c73dd6c372a450b5f42dbe184c368e260a45
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/265597
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Mike Reed <reed@google.com>
4 files changed