Add load/store to SkRasterPipeline for 16161616 unsigned normalized.

Bug: skia:8962

Change-Id: I0ab208063b6b7eca010f86d4d851ade23df5f849
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/220529
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
3 files changed