Fix GPU flag in Swarming VM creation
Fix GPU flag in Swarming VM creation

BUG=skia:6612

Change-Id: I763be011f400686816e40802f7bcce4473f9b644
Reviewed-on: https://skia-review.googlesource.com/19621
Reviewed-by: Ben Wagner <3ef7217be91069877d94f7907ce5479000772cd3@google.com>
Reviewed-by: Eric Boren <0e499112533c8544f0505ea0d08394fb5ad7d8fa@google.com>
Commit-Queue: Ravi Mistry <9fa2e7438b8cb730f96b74865492597170561628@google.com>

google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot