Remove Vulkan code that supported creating a GrVkRenderTarget.

We never create a pure RenderTarget. If we are creating a RT it is always
a TexRT. The only pure RTs are wrapped.

Bug: skia:
Change-Id: If95d17d244e78c986ed6c63822d4b936ff67b88a
Reviewed-on: https://skia-review.googlesource.com/137700
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
2 files changed