mem-ruby: Deallocating unused entries in MOESI_CMP L2

mem-ruby: Deallocating unused entries in MOESI_CMP L2

Invalid entries are never removed from the directories in the L2
controller. This patch fixes this by deallocating the entries
when they become invalid. The NP (not present) state was removed
since it's now equivalent to Invalid.

Change-Id: Id807b341a2aadb06008491545aca614d5a09b8df
Signed-off-by: Tiago Mück <tiago.muck@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/21922
Reviewed-by: Pouya Fotouhi <pfotouhi@ucdavis.edu>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>