configs,mem-ruby: Remove reference to old GPU ptls

GPU_VIPER_Baseline, GPU_VIPER_Region, and GPU_RfO were removed some time
ago.

Change-Id: If873b0cfe8cc2b3096cbe97d4e13a8e02d2ec567
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/53703
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Reviewed-by: Matt Sinclair <mattdsinclair@gmail.com>
Maintainer: Matt Sinclair <mattdsinclair@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
2 files changed