mem-ruby: Allow MessageBuffer functional reads

Valid lines withing unhandled messages may need to be checked when the
line is in a transient state.

Change-Id: I433e9bb960680348c25bf19ace2d405109380241
Signed-off-by: Tiago Mück <tiago.muck@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/22019
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Bradford Beckmann <brad.beckmann@amd.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
2 files changed