gpu-compute,mem-ruby: Replace ACQUIRE and RELEASE request flags

gpu-compute,mem-ruby: Replace ACQUIRE and RELEASE request flags

This patch replaces ACQUIRE and RELEASE flags which are HSA-specific.
ACQUIRE flag becomes INV_L1 in VIPER protocol. RELEASE flag is removed.
Future protocols may support extra cache coherence flags like INV_L2 and
WB_L2.

Change-Id: I3d60c9d3625c898f4110a12d81742b6822728533
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/32859
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Reviewed-by: Matt Sinclair <mattdsinclair@gmail.com>
Maintainer: Matt Sinclair <mattdsinclair@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>