cpu: Use enums for O3CPU store value forwarding

This is aligning with MinorCPU, where an enum is tagging a Full, Partial
and No address coverage.

Change-Id: I0e0ba9b88c6f08c04430859e88135c61c56e6884
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/23951
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
Tested-by: kokoro <noreply+kokoro@google.com>
1 file changed