Hoist up uniform GrRingBuffer to GrGpu

Change-Id: Ib829c883c260ef8ff4a3f5326922d66476b7306f
Bug: skia:10530
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/306949
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
5 files changed