mem-cache: Cleanup of SBOOE prefetcher

mem-cache: Cleanup of SBOOE prefetcher

Made the latencyBuffer a CircularQueue.

Improved encapsulation of the Sandbox struct.

Fixed score() to follow function declaration guidelines.

Removed redundant fatal error checking for score threshold.

Change-Id: I1904884e96f103c67930abafc28b75796aadc406
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/24541
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>