Don't take initial buffer data in GrGpu::createBuffer.

Bug: skia: 12720
Change-Id: I1d025689e4c977fe487989f8c7a3200b3c9c9e1a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/544245
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
17 files changed