Specify more specific CPU dimensions.

This is required in order to add Skylake GCE machines, in order to
avoid existing Perf GCE tasks from switching between Haswell and
Skylake.

Bug: skia:6326
Change-Id: Ib05323f5476c7b9a40d9f752c5a7ee8731c4185d
Reviewed-on: https://skia-review.googlesource.com/50740
Reviewed-by: Mike Klein <mtklein@chromium.org>
Reviewed-by: Eric Boren <borenet@google.com>
Commit-Queue: Ben Wagner <benjaminwagner@google.com>
2 files changed