Remove unused copySurfaceAsDraw code from GrVkGpu

The actual implementation of this lives in GrVkCopyManager now

BUG=skia:

Change-Id: I8b0577acef3ac3b9e835605d4044336975a96ee5
Reviewed-on: https://skia-review.googlesource.com/5390
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
2 files changed