Delete deprecated arithmetic filter header

Bug: skia:11230
Change-Id: I966d9511d6124627308146f1b5f9e18f5d7fb4d0
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/368241
Auto-Submit: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
9 files changed