Revert "[graphite] Add caps to support readPixels and writePixels."

This reverts commit 54076422cc483dd7d5b406af64c1ee9f65d4609c.

Reason for revert: Vulkan conflict

Original change's description:
> [graphite] Add caps to support readPixels and writePixels.
>
> Adds the checks for base support, and the colortype needed.
>
> Bug: b/238756873
> Change-Id: I77f29a610a5411eba2017d3aaf59c62a3a05b53a
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/589116
> Commit-Queue: Jim Van Verth <jvanverth@google.com>
> Reviewed-by: Greg Daniel <egdaniel@google.com>

Bug: b/238756873
Change-Id: I1f7af09f7d1064cce25184b0866d7ad88737f094
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/589400
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Auto-Submit: Robert Phillips <robertphillips@google.com>
6 files changed