mem-ruby: Fix debug prints for regular Stores

mem-ruby: Fix debug prints for regular Stores

In the updated implementation of LL/SC (27103) the default value
of success was changed, which results in printing "SC_Failed" for
any regular stores.

Change-Id: I4f2e0b26233ce0cbdf948aadd19c9d81bf18bec0
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/32514
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>