remove RP bench

Originally I wanted to get it away from using from_srgb/to_srgb
directly, but in the end I just don't care about any of it.

Change-Id: I7ed39a92840f02c98bfe97203bef64057ee0413e
Reviewed-on: https://skia-review.googlesource.com/c/165440
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
2 files changed