mem-garnet: Use smart pointers in Router's members

mem-garnet: Use smart pointers in Router's members

Use smart pointers for the pointers managed by Router, and do
static allocation when possible.

Change-Id: I5fad8b2d17ac7950d478d37000ac80a4d2f68b15
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/24248
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Reviewed-by: Srikant Bharadwaj <srikant.bharadwaj@amd.com>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>