mem-cache: Add a data-update probe to cache

mem-cache: Add a data-update probe to cache

This probe is responsible for notifying any changes to the
data contents of a block. This includes fills, overwrites,
and invalidations/evictions.

Jira: https://gem5.atlassian.net/browse/GEM5-814

Change-Id: I1ff3c09c63d5402765c2125c4d76d95b614877d6
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/37096
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>