Rename SwiftShader bots from CPU to GPU.

Bug: skia:7671
Change-Id: I1d6b2a07ca93acbe53c1e93d70335f5284cd494e
NoTry: true
Reviewed-on: https://skia-review.googlesource.com/129500
Commit-Queue: Ben Wagner <benjaminwagner@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Reviewed-by: Eric Boren <borenet@google.com>
7 files changed