mem-ruby: Deallocating unused entries in MOESI_CMP dir

mem-ruby: Deallocating unused entries in MOESI_CMP dir

Invalid entries are never removed from the directory the Directory
controller. This patch fixes this by deallocating the entries
when they become invalid.

Change-Id: I616686a78c5eddb7748192bf94bb691a4f158cbc
Signed-off-by: Tiago Mück <tiago.muck@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/27847
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Pouya Fotouhi <pfotouhi@ucdavis.edu>