cleanup SK_GPU_V1 guards

Change-Id: I2dff774d67f55de7b98ccc650f9e8bc19bebd762
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/467757
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Herb Derby <herb@google.com>
4 files changed